Gas fuel injection valve

Abstract

To protect a seal member while ensuring the injection performance of gas fuel.SOLUTION: In a fuel injection valve, a nozzle body 12 has an end plate portion 33 that divides upstream and downstream fuel passages P1, P2, and a communication hole 34 is provided in the end plate portion 33 to provide communication between the fuel passages P1, P2. The fuel injection valve is provided with an upper stage opening / closing valve 13 that opens and closes the communication hole 34 from the upstream side, a lower stage opening / closing valve 14 that opens and closes the communication hole 34 from the downstream side, and a seal member 27 that seals the communication hole 34 between the upper stage opening / closing valve 13 and an end plate portion 33. The upper stage opening / closing valve 13 is driven to open by a coil 25, while the lower stage opening / closing valve 14 is opened when the pressure in the communication hole 34 becomes higher than the biasing force of a second spring 45. In addition, the fuel injection valve has a configuration in which gas fuel that flows out of the communication hole 34 and adiabatically expands when the lower stage opening / closing valve 14 is opened is collided with an extension portion extending downstream from the end plate portion 33, thereby cooling the extension portion.SELECTED DRAWING: Figure 3

Description

Technical Field

[0004] ,

[0001] The disclosure in this specification relates to a gas fuel injection valve.

Background Art

[0002] As a gas fuel injection valve used in a direct injection gas engine, for example, a gas metering valve described in Patent Document 1 is known. In this gas metering valve, while suppressing the leakage of gas fuel by providing an elastomer seal member on an actuator-driven valve member, in order to suppress damage to the seal member due to heat and pressure generated during combustion of the gas engine, the seal position of the valve member is made to be far from the fuel outflow opening. Further, in the gas metering valve, by providing a check valve (passive on-off valve) that opens by the pressure difference between the upstream side and the downstream side between the actuator-driven valve member and the outflow opening, it is intended to suppress the propagation of the flame and combustion pressure in the combustion chamber to the seal member. Thereby, it is said that the seal member made of elastomer is effectively protected.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the technique described in Patent Document 1 above increases the distance between the valve member provided with the seal member and the check valve on its downstream side, and the volume between these valve member and the check valve has increased. Therefore, it is considered that the closing responsiveness of the check valve when the upstream valve member closes is low, and gas leakage occurs in the fuel injection valve due to the decrease in the responsiveness, and as a result, abnormal combustion in the gas engine may occur. On the other hand, if the upstream valve member having a sealing function is installed closer to the check valve, there is a concern about heat damage to the seal member of the valve member.

[0005] This disclosure has been made in view of the above circumstances and aims to provide a gas fuel injection valve that can protect the sealing member while ensuring the injection performance of the gas fuel. [Means for solving the problem]

[0006] This disclosure is, A gas fuel injection valve that directly injects gaseous fuel into the combustion chamber of an internal combustion engine, It has a cylindrical shape, a main body having a fuel passage inside and a nozzle at its tip, The main body has a partition that divides the fuel passage into an upstream first fuel passage and a downstream second fuel passage, and the partition is provided with a communication hole that connects the first fuel passage and the second fuel passage. 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 sealing member that seals the area around the opening of the communication hole between the first on-off valve and the compartment. The first on-off valve is driven to open by a drive unit, while the second on-off valve opens when the pressure in the communication hole becomes higher than the biasing force of the biasing member that biases the second on-off valve to the closed side. The system is configured such that when the second on-off valve opens, the gas fuel that flows out from the communication hole and undergoes adiabatic expansion collides with an extension that extends downstream from the compartment, thereby cooling the extension.

[0007] In the fuel injection valve with the above configuration, the cylindrical body has a first fuel passage on the upstream side of the compartment and a second fuel passage on the downstream side, and the first and second fuel passages are connected by a communication hole. When the drive unit opens the first on-off valve, the communication hole is opened from the first fuel passage side, and when the pressure inside the communication hole rises 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 both the upstream and downstream sides, gaseous fuel is injected by the fuel injection valve. In this case, a sealing member is provided between the first on-off valve and the compartment to seal around the opening of the communication hole, which improves gas sealing performance compared to a configuration in which the first on-off valve and the compartment are in direct contact when the first on-off valve is closed.

[0008] Furthermore, when the second on-off valve opens and gas fuel flows out from the communication hole, adiabatic expansion of the gas fuel occurs, and the compartment is cooled by the gas fuel whose temperature has decreased due to this adiabatic expansion. In other words, when the second on-off valve opens and the gas fuel flows out from the communication hole and undergoes adiabatic expansion, it collides with the extension that extends downstream from the compartment, cooling the extension, and the compartment is further cooled as the extension cools. As the compartment cools, the seal member located on the opposite side of the second on-off valve (the side of the first on-off valve) across the compartment is cooled. In this case, although the seal member is located relatively close to the second on-off valve, separated only by the compartment, excessive temperature rise of the seal member is suppressed. Also, since the upstream and downstream on-off valves are located relatively close to each other across the compartment, a decrease in responsiveness is suppressed in the passive second on-off valve. As a result, the seal member can be protected while ensuring the gas fuel injection performance. [Brief explanation of the drawing]

[0009] [Figure 1] Longitudinal cross-sectional view of a fuel injection valve. [Figure 2] Perspective view of the second cylinder section. [Figure 3] A close-up vertical cross-sectional view showing the nozzle body and the lower on / off valve. [Figure 4]Cross-sectional view of line 4-4 in Figure 3. [Figure 5] Perspective view of the lower on / off valve. [Figure 6] A longitudinal cross-sectional view showing the fuel injection valve in the open position. [Figure 7] A longitudinal cross-sectional view showing an enlarged view of the nozzle body and the lower on / off valve in another example. [Figure 8] A longitudinal cross-sectional view showing the configuration of a fuel injection valve in another example. [Modes for carrying out the invention]

[0010] Hereinafter, an embodiment of the gas fuel injection valve according to this 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 hydrogen, CNG (Compressed Natural Gas), or LNG (Liquefied Natural Gas) as the 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 on-board engine. The fuel injection system of this embodiment is a so-called low-pressure direct injection system in which gas fuel compressed to about a few MPa is injected into the combustion chamber from the fuel injection valve.

[0011] The configuration of the fuel injector 10 will be explained using Figure 1. In the following explanation, the axis extending in the longitudinal direction of the fuel injector 10 and forming the center of the cross-section will be used as the reference point. The direction in which this axis extends will be called the axial direction, the direction radiating from the axis will be called the radial direction, and the direction circumferentially extending around the axis will be called the circumferential direction. Also, in Figure 1, the right side is the base end (upstream side) of the fuel injector 10, and the left side is the tip end (downstream side).

[0012] The fuel injector 10 comprises, in general terms, a housing 11, a nozzle body 12 located further forward than 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 drive, and the lower on-off valve 14 is a passive downstream on-off valve that opens due to the pressure difference between the upstream and downstream sides. In the fuel injector 10, the lower on-off valve 14 opens in response to the opening of the upper on-off valve 13, and gaseous fuel is injected from the injection hole 15 by the opening of these on-off valves 13 and 14. The housing 11 and nozzle body 12 correspond to the "main body," the upper on-off valve 13 corresponds to the "first on-off valve," and the lower on-off valve 14 corresponds to the "second on-off valve."

[0013] Although not shown because it is a known configuration, the fuel injector 10 is assembled to the gas engine such that its tip (nozzle body 12) is exposed into the combustion chamber, and the fuel injector 10 directly injects gaseous fuel into the combustion chamber. The configuration of each part of the fuel injector 10 will be described in detail below.

[0014] The housing 11 is formed in a cylindrical shape, and a fixed core 21 is fixed within its hollow portion. The upper on-off valve 13 is housed in a position aligned axially with the fixed core 21, in a manner that allows for reciprocating motion. The upper on-off valve 13 consists of a movable core. The fixed core 21 is cylindrical in shape, and a first spring 22, which is a compression coil spring, is positioned inside it. The first spring 22 is provided between the spring receiving portion 21a of the fixed core 21 and the axial end face of the upper on-off valve 13. The first spring 22 biases the upper on-off valve 13 toward the tip side of the fuel injection valve 10 (i.e., in the direction that closes the communication hole 34, which will be described later, from the base end side).

[0015] The fixed core 21 has a hollow portion 21b, and the upper on-off valve 13 has a hollow portion 13a. These hollow portions 21b and 13a extend in the axial direction and communicate with each other. When gas fuel is supplied from a fuel pipe provided on the base end side of the fixed core 21, the gas fuel is introduced to the tip side of the upper on-off valve 13 through the upstream fuel passage P1 formed by the hollow portions 21b and 13a of the fixed core 21 and the upper on-off valve 13. In the present 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.

[0016] Further, a coil 25 is provided in the housing 11 as a drive unit of 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 due to the magnetic energy, the upper on-off valve 13 is displaced to the valve opening side against the biasing force of the first spring 22.

[0017] A nozzle body 12 is provided on the downstream side of the upper on-off valve 13. The nozzle body 12 has a first cylindrical portion 31 on the tip side and a second cylindrical portion 32 on the base end side, and the inner peripheral sides of these cylindrical portions 31 and 32 form the downstream fuel passage P2. One end side in the axial direction in the first cylindrical portion 31 is a spray hole 15. The second cylindrical portion 32 has an end plate portion 33 provided at the base end side end portion. 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 partitioning portion in the fuel injection valve 10 that partitions the upstream fuel passage P1 formed by the fixed core 21 and the upper on-off valve 13 and the downstream fuel passage P2 formed by the nozzle body 12, and the communication holes 34 are communication passages that connect these upstream and downstream fuel passages P1 and P2. Note that the end plate portion 33 is a pressure partition for preventing the pressure generated by combustion in the engine combustion chamber from propagating to the upstream fuel passage P1.

[0018] FIG. 2 is a perspective view of the second cylindrical portion 32. As shown in FIG. 2, the second cylindrical portion 32 is provided with a peripheral wall portion 35 that extends toward the downstream side (the left side in the figure) on the outer peripheral portion of the end plate portion 33. Further, a plurality of communication holes 34 are provided in a circumferential shape along the peripheral wall portion 35 on the end plate portion 33. The communication holes 34 are each formed in an arc shape extending in the circumferential direction. However, the opening shape of each communication hole 34 may be arbitrary, and for example, it may have a circular opening shape.

[0019] Returning to the description of FIG. 1, an annular plate-shaped seal member 27 is fixed to the axial end face of the upper opening / closing valve 13 at a position facing the opening of each communication hole 34. In a state where the upper opening / closing valve 13 is closed by the biasing force of the first spring 22 (the state in FIG. 1), the seal member 27 abuts against the seat surface 33a, which is the axial end face of the end plate portion 33, and the first opening, which is the upstream-side opening of the communication hole 34, is closed by the seal member 27. Then, when the upper opening / closing valve 13 is displaced toward the open valve side, the seal member 27 separates from the seat surface 33a of the end plate portion 33, and the first opening is opened. The seal member 27 is formed of any of elastic materials having elasticity, such as a rubber material, a resin material, an elastomer material, etc. More specifically, fluorine-based rubber, EPDM (ethylene propylene diene rubber), etc. may be used as the seal material.

[0020] Inside the nozzle body 12, a lower opening / closing valve 14 for opening and closing the communication hole 34 from the fuel passage P2 side is provided. The lower opening / closing valve 14 has a cylindrical portion 41 and a flange-shaped opening / closing portion 42 that extends in the radial direction and is provided on one axial end side of the cylindrical portion 41. The cylindrical portion 41 is a sliding portion that can slide axially along the inner peripheral surface of the first cylindrical portion 31, and the opening / closing portion 42 is a closing plate portion that closes the second opening, which is the downstream-side opening of the communication hole 34. The opening / closing portion 42 is liftable between a position where it closes the second opening (downstream-side opening) of the communication hole 34 and a position where it opens. In the present 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.

[0021] A second spring 45, made of a compression coil spring, is positioned between the opening closing portion 42 and the axial end face of the first cylindrical portion 31. The second spring 45 biases the lower on-off valve 14 toward the base end side of the fuel injection valve 10 (i.e., in the direction of closing the communication hole 34 from the tip side). The lower on-off valve 14 opens when the pressure inside the communication hole 34 becomes greater than the biasing force of the second spring 45. The second spring 45 corresponds to the "biasing member".

[0022] The lower on-off valve 14 may be made of a metal, non-metallic, or other non-elastomer material with excellent heat resistance. The opening closing portion 42 is pressed against the downstream opening of the communication hole 34, thereby suppressing leakage of gas fuel from the communication hole 34 and also suppressing the inflow of flames and combustion pressure into the combustion chamber.

[0023] In the end plate portion 33, the communication hole 34 is closed from the fuel passage P1 side, which is one axial side, by the upper on-off valve 13, and the communication hole 34 is closed from the fuel passage P2 side, which is the other axial side, by the lower on-off valve 14. The upper on-off valve 13 is an inward-opening valve that opens towards the base end of the fuel injection valve 10, and the lower on-off valve 14 is an outward-opening valve that opens towards the tip side of the fuel injection valve 10.

[0024] In the fuel injection valve 10, when the coil 25 is energized, the upper on-off valve 13 is displaced to the open side, causing gaseous fuel in the upstream fuel passage P1 to flow into the communication hole 34, and the pressure inside the communication hole 34 to rise. When the pressure inside the communication hole 34 exceeds the biasing force of the second spring 45, the lower on-off valve 14 is displaced to the open side. In this case, when both on-off valves 13 and 14 on either side of the communication hole 34 are open, gaseous fuel flows from the upstream fuel passage P1 to the downstream fuel passage P2, and gaseous fuel is then injected from the injection hole 15 at the tip of the fuel passage P2.

[0025] In the fuel injection valve 10 of this embodiment, after the upper on-off valve 13 is closed, gaseous fuel remains in the communication holes 34 provided in the end plate portion 33 until the upper on-off valve 13 is opened again. In this case, the total volume of the multiple communication holes 34 provided in the end plate portion 33 is the volume of residual gas remaining downstream of the upper on-off valve 13 after the upper on-off valve 13 is closed and until the upper on-off valve 13 is opened again.

[0026] Next, the configuration relating to the outflow of gas fuel from the communication hole 34 when the lower on-off valve 14 opens will be explained in detail. Figure 3 is an enlarged longitudinal cross-sectional view showing the nozzle body 12 and the lower on-off valve 14, and Figure 4 is a transverse cross-sectional view taken along line 4-4 in Figure 3. In Figure 4, the communication hole 34 of the end plate portion 33 is shown with a dashed line. Figure 5 is a perspective view of the lower on-off valve 14.

[0027] As shown in Figure 3, in the nozzle body 12, a sliding surface 36 is formed on the inner circumference of the first cylindrical portion 31, which allows the cylindrical portion 41 of the lower on-off valve 14 to slide. In addition, an enlarged inner circumferential surface 37, which is larger in diameter than the sliding surface 36, is formed on the inner circumference of both the first cylindrical portion 31 and the second cylindrical portion 32. As a result, the inner circumference of the peripheral wall portion 35 becomes an expanded space S1 that expands radially outward in the uppermost part of the fuel passage P2 (i.e., a predetermined range on the uppermost side). In other words, in the nozzle body 12, the passage diameter differs between the uppermost part of the fuel passage P2 and the downstream side, and the passage diameter is expanded in the uppermost part to form an annular expanded space S1. In relation to the lower on-off valve 14, the expanded space S1 is formed radially outward of the cylindrical portion 41.

[0028] The second spring 45 is housed in the expansion space S1. The enlarged inner circumferential surface 37 and the expansion space S1 formed by the enlarged inner circumferential surface 37 may be formed by the first cylindrical portion 31 and the second cylindrical portion 32, or by the second cylindrical portion 32 alone, as long as it is located downstream from the end plate portion 33 in the nozzle body 12.

[0029] Furthermore, a projection 38 is provided at the center of the downstream end face of the end plate portion 33, projecting downstream. The projection 38 is provided on the radially inward side of the peripheral wall portion 35, and more precisely, on the radially inward side of the cylindrical portion 41 of the lower on-off valve 14 within the radially inward side of the peripheral wall portion 35. The projection 38 is formed in a conical shape. However, the shape of the projection 38 is arbitrary and may be cylindrical, prismatic, pyramidal, etc., and multiple projections 38 may be provided. Note that the peripheral wall portion 35 and the projection 38 correspond to the "extension portion".

[0030] Here, as shown in Figure 4, if we let D1 be the outer diameter of the cylindrical portion 41 of the lower on-off valve 14 (in other words, the inner diameter of the sliding surface 36 of the first cylindrical portion 31), D2 be the inner diameter of the enlarged inner circumferential surface 37, and D3 be the outer diameter of the opening / closing portion 42 of the lower on-off valve 14, then each of these dimensions is D1<D3、D2> The relationship is D3. In other words, the inner diameter dimension D2 of the enlarged 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 expanded space S1. Furthermore, because the inner diameter dimension D2 of the enlarged inner circumferential surface 37 is larger than the outer diameter dimension D3 of the opening closing portion 42, it is possible to form a radial gap between the enlarged inner circumferential surface 37 and the outer circumference of the opening closing portion 42.

[0031] 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 closing portion 42. That is, the opening closing portion 42 has a portion that protrudes radially outward from the opening of the communication hole 34 and a portion that protrudes radially inward, and these protruding portions guide the gas fuel flowing out from the communication hole 34 radially inward and radially outward, respectively. The opening closing portion 42 corresponds to a "guide portion". At this time, the gas fuel flowing radially outward proceeds so as to collide with the enlarged inner circumferential surface 37 (the inner circumferential surface of the circumferential wall portion 35) and is introduced into the expanded space S1 through the gap between the enlarged inner circumferential surface 37 and the outer circumferential portion of the opening closing portion 42. The gas fuel flowing radially inward proceeds so as to collide with the protruding portion 38 of the end plate portion 33.

[0032] Furthermore, the cylindrical portion 41 of the lower on-off valve 14 is provided with a plurality of openings 43 at predetermined intervals in the circumferential direction (see Figure 5). As a result, the inside and outside of the cylindrical portion 41, that is, the expanded space S1 and the inner space radially inside it, are in communication through the openings 43.

[0033] Figure 6 is a diagram illustrating the flow of gaseous fuel when the fuel injection valve 10 is open. In Figure 6, both the upper on-off valve 13 and the lower on-off valve 14 of the fuel injection valve 10 are open, and the flow of gaseous fuel is indicated by arrows.

[0034] When the lower on-off valve 14 opens, the opening closing portion 42 separates from the downstream end face (downstream seat surface) of the end plate portion 33, causing gas fuel to flow out from the communication hole 34. At this time, the temperature of the gas fuel decreases due to adiabatic expansion. Specifically, in a gas engine, gas fuel is injected from the fuel injection valve 10 during at least one of the intake stroke and compression stroke. During this fuel injection, as the lower on-off valve 14 opens and gas fuel flows out from the communication hole 34, the pressure of the gas fuel is reduced from several MPa to near atmospheric pressure. For example, if the gas supply pressure is 2 MPa or higher, the gas temperature is expected to drop by 100°C or more due to adiabatic expansion.

[0035] The gas fuel flowing out from the communication hole 34 strikes the flat opening closing portion 42 and flows radially outward and radially inward. In other words, the gas fuel flowing out from the communication hole 34 is guided radially outward and radially inward by the opening closing portion 42 of the lower on-off valve 14. The gas fuel guided radially outward collides with the inner 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 flowing out from 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 the temperature rise of the sealing member 27. In particular, immediately after flowing out from the communication hole 34, the gas fuel is guided radially outward, then changes direction to radially inward, and its path meanders radially. Therefore, heat exchange with respect to the second cylindrical portion 32 is promoted.

[0036] Furthermore, a second spring 45 is provided in the expansion space S1, and the second spring 45 is cooled by the gaseous 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 of the engine combustion chamber.

[0037] Furthermore, the gas fuel guided radially inward after the lower on-off valve 14 opens collides with the protrusion 38 in the center of the end plate portion 33. As a result, the end plate portion 33 is cooled by the gas fuel, which has also undergone adiabatic expansion, and the temperature rise of the sealing member 27 is suppressed.

[0038] According to the embodiment described in detail above, the following excellent effects can be obtained.

[0039] In the fuel injection valve 10, a sealing member 27 is provided between the upper on-off valve 13 and the end plate portion 33 to seal the area around the opening of the communication hole 34. This improves the gas sealing performance compared to a configuration in which the upper on-off valve 13 and the end plate portion 33 are in direct contact when the upper on-off valve 13 is in the closed state.

[0040] Furthermore, when the lower valve 14 opens and gas fuel flows out from the communication hole 34, adiabatic expansion of the gas fuel occurs, and the end plate portion 33 is cooled by the gas fuel whose temperature has decreased due to this adiabatic expansion. As the end plate portion 33 cools, the sealing member 27, which is located on the opposite side of the lower valve 14 (the side of the upper valve 13) across the end plate portion 33, is also cooled. In this case, although the sealing member 27 is located relatively close to the lower valve 14, separated only by the end plate portion 33, an excessive temperature rise of the sealing member 27 is suppressed. In addition, since the upstream and downstream valves 13 and 14 are located relatively close to each other across the end plate portion 33, a decrease in responsiveness in the passive lower valve 14 is suppressed. As a result, the sealing member 27 can be protected while ensuring the gas fuel injection performance.

[0041] 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 flows out from the communication hole 34 and undergoes adiabatic expansion radially outward and radially inward, respectively, so that it collides with the peripheral wall portion 35 and the protruding portion 38. In this case, the gas fuel, whose temperature has decreased due to adiabatic expansion, collides with the peripheral wall portion 35 and the protruding portion 38, respectively, thereby cooling the second cylindrical portion 32. This promotes the cooling of the end plate portion 33 and suppresses the temperature rise of the sealing member 27.

[0042] 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 even with a simple configuration.

[0043] Within the nozzle body 12, an annular expansion space S1 is formed at the uppermost upstream side of the fuel passage P2 by expanding the passage diameter, 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 decreased due to 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 the temperature rise of the sealing member 27.

[0044] The lower on-off valve 14 is configured to have an opening 43 in its cylindrical portion 41 that connects the expansion space S1 with the inner space radially inside it. In this case, the gas fuel, whose temperature has decreased due to adiabatic expansion when the lower on-off valve 14 is opened, flows through the expansion space S1 and then through the opening 43 in the cylindrical portion 41 to the inner space. This causes the gas fuel to meander radially within the fuel passage P2, promoting heat exchange with the second cylindrical portion 32.

[0045] A second spring 45 is provided in the expanded space S1 to bias the lower on-off valve 14 towards the closed position. In this configuration, the second spring 45 is cooled by the gaseous fuel whose temperature has decreased due to adiabatic expansion. This reduces the thermal load on the second spring 45, which is exposed to the flames of the engine combustion chamber.

[0046] The total volume of the multiple communication holes 34 provided in the end plate portion 33 of the second cylindrical portion 32 is configured to be the volume of residual gas remaining downstream of the upper on-off valve 13 between the closing of the upper on-off valve 13 and the next time the upper on-off valve 13 is opened. In other words, the end plate portion 33 only needs to partition the upstream and downstream fuel passages P1 and P2 and have a plate thickness that can withstand pressure waves from the engine combustion chamber, and only the volume of the communication holes 34 corresponding to that plate thickness is the volume of residual gas downstream of the upper on-off valve 13. In this case, unlike existing structures in which a spring or the like is interposed between the upper on-off valve 13 and the lower on-off valve 14, the residual gas volume can be reduced, and consequently the responsiveness of the fuel injection valve 10 can be improved.

[0047] (Other embodiments) The above embodiment may be modified as follows, for example.

[0048] In the above embodiment, the peripheral wall portion 35 and the protruding portion 38 of the nozzle body 12 were used as targets (extensions) upon which the gas fuel after adiabatic expansion would collide, but this configuration may be changed. For example, only the peripheral wall portion 35 may be used as the target (extension) upon which the gas fuel after adiabatic expansion would collide. Specifically, as shown in Figure 7, the opening closing portion 42 of the lower on-off valve 14 is made into a disc shape with no opening in the center, and the protruding portion 38 of the end plate portion 33 is removed. In this case, the opening closing portion 42 of the lower on-off valve 14 guides the gas fuel that flows out from the communication hole 34 and has undergone adiabatic expansion toward the radially outward direction and collides with the peripheral wall portion 35. As a result, the end plate portion 33 is cooled together with the peripheral wall portion 35, and the temperature rise of the sealing member 27 is suppressed.

[0049] The fuel injection valve 10 may be configured as shown in Figure 8. In Figure 8, the main body is cylindrical, and the end plate portion 33 (compartment portion) is fixed to the middle part. Figure 8 shows the state in which both the upper on-off valve 13 and the lower on-off valve 14 are open.

[0050] In Figure 8, a communication hole 34 is provided in the center of the disc-shaped end plate portion 33. This 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 the second spring 45 to close the downstream opening of the communication hole 34. In this configuration as well, the lower on-off valve 14 guides the gas fuel that flows out from the communication hole 34 and undergoes adiabatic expansion radially outward. The end plate portion 33 is cooled together with the peripheral wall portion 35 by collision between the gas fuel and the peripheral wall portion 35, thereby suppressing the temperature rise of the sealing member 27. The surface of the lower on-off valve 14 facing the end plate portion 33 corresponds to the "guide portion".

[0051] In the above embodiment, a sealing member 27 is provided between the upper on-off valve 13 and the end plate portion 33, and the sealing member 27 is fixed to the axial end face of the upper on-off valve 13. However, this can be changed. For example, the sealing member 27 may be fixed to the end plate portion 33.

[0052] The drive unit for driving the upper on-off valve 13 may also be configured to use a motor instead of the coil 25.

[0053] The technical concepts extracted from the above-described embodiments are described below. [Configuration 1] A gas fuel injector (10) that directly injects gaseous fuel into the combustion chamber of an internal combustion engine, It comprises a cylindrical body (11, 12) having a fuel passage inside and a nozzle (15) at its tip, The main body has a partition (33) that divides the fuel passage into an upstream first fuel passage (P1) and a downstream second fuel passage (P2), and the partition is provided with a communication hole (34) that connects the first fuel passage and the second fuel passage. The main body is provided with a first on-off valve (13) that opens and closes the communication hole from the first fuel passage side, a second on-off valve (14) that opens and closes the communication hole from the second fuel passage side, and a sealing member (27) that seals the area around the opening of the communication hole between the first on-off valve and the compartment. The first on-off valve is driven to open by the drive unit (25), while the second on-off valve opens when the pressure in the communication hole becomes higher than the biasing force of the biasing member (45) that biases the second on-off valve to the closed side. A gas fuel injection valve having a configuration that causes the gas fuel that flows out from the communication hole and undergoes adiabatic expansion upon opening of the second on-off valve to collide with extensions (35, 38) extending downstream from the compartment, thereby cooling the extensions. [Configuration 2] The main body portion has a peripheral wall portion (35) that extends downstream from the outer periphery of the compartment portion and forms the second fuel passage, and a projection portion (38) that protrudes downstream at a position radially inward of the peripheral wall portion on the downstream end face of the compartment portion, and these peripheral wall portion and projection portion constitute the extension portion. The partitioned portion is provided with the communication hole between the peripheral wall portion and the protruding portion. The gas fuel injection valve according to configuration 1, wherein the second on-off valve has a guide portion (42) that guides the gas fuel that flows out from the communication hole and undergoes adiabatic expansion toward the radially outward and radially inward directions, respectively, and causes it to collide with the peripheral wall portion and the protruding portion. [Configuration 3] The main body portion extends downstream from the outer periphery of the partition portion and has a peripheral wall portion (35) that forms the second fuel passage, and the peripheral wall portion is the extension portion. The gas fuel injection valve according to configuration 1, wherein the second on-off valve has a guide portion (42) that guides the gas fuel that flows out from the communication hole and undergoes adiabatic expansion radially outward and causes it to collide with the peripheral wall. [Structure 4] In the main body, the diameter of the second fuel passage differs between the uppermost part and the downstream side, and the passage diameter is expanded in the uppermost part to form an annular expansion space (S1). The gas fuel injection valve according to configuration 2 or 3, wherein the guide portion of the second on-off valve guides the gas fuel that flows out from the communication hole and undergoes adiabatic expansion toward the radially outward direction and introduces it into the expanded space. [Composition 5] The second on-off valve has a cylindrical portion (41) that is slidable against the inner circumferential surface of the main body, and the expansion space is formed radially outward of the cylindrical portion. The gas fuel injection valve according to configuration 4, wherein the cylindrical portion has an opening (43) that communicates the expanded space with the inner space radially inside it. [Composition 6] The gas fuel injection valve according to configuration 4 or 5, wherein the expanded space is provided with a biasing member (45) that biases the second on-off valve to the closed side. [Composition 7] A gas fuel injection valve according to any one of configurations 1 to 6, wherein the total volume of the plurality of communication holes provided in the compartment is the volume of residual gas remaining downstream of the first on-off valve after the first on-off valve is closed and before the first on-off valve is opened again. [Explanation of Symbols]

[0054] 10...Fuel injection valve, 11...Housing, 12...Nozzle body, 13...Upper on / off valve, 14...Lower on / off valve, 15...Injection hole, 25...Coil, 27...Sealing member, 33...End plate portion, 34...Communication hole, 35...Peripheral wall portion, 38...Protrusion portion, P1, P2...Fuel passage.

Claims

1. A gas fuel injection valve (10) that directly injects gaseous fuel into the combustion chamber of an internal combustion engine, It comprises a cylindrical body (11, 12) having a fuel passage inside and a nozzle (15) at its tip, The main body has a partition (33) that divides the fuel passage into an upstream first fuel passage (P1) and a downstream second fuel passage (P2), and the partition is provided with a communication hole (34) that connects the first fuel passage and the second fuel passage. The main body is provided with a first on-off valve (13) that opens and closes the communication hole from the first fuel passage side, a second on-off valve (14) that opens and closes the communication hole from the second fuel passage side, and a sealing member (27) that seals the area around the opening of the communication hole between the first on-off valve and the compartment. The first on-off valve is driven to open by the drive unit (25), while the second on-off valve opens when the pressure in the communication hole becomes higher than the biasing force of the biasing member (45) that biases the second on-off valve to the closed side. The system has a configuration in which the gas fuel that flows out from the communication hole and undergoes adiabatic expansion upon opening of the second on-off valve collides with the extensions (35, 38) that extend downstream from the compartment, thereby cooling the extensions. Furthermore, the main body portion has a peripheral wall portion (35) that extends downstream from the outer periphery of the compartment portion and forms the second fuel passage, and a projection portion (38) that protrudes downstream at a position on the downstream end face of the compartment portion that is radially inward of the peripheral wall portion, and these peripheral wall portion and projection portion constitute the extension portion. The partitioned portion is provided with the communication hole between the peripheral wall portion and the protruding portion. The second on-off valve is a gas fuel injection valve having a guide portion (42) that guides the gas fuel that flows out from the communication hole and undergoes adiabatic expansion radially outward and radially inward, respectively, and causes it to collide with the peripheral wall portion and the protruding portion.

2. In the main body, the diameter of the second fuel passage differs between the uppermost part and the downstream side, and the passage diameter is expanded in the uppermost part to form an annular expansion space (S1). The gas fuel injection valve according to claim 1, wherein the guide portion of the second on-off valve guides the gas fuel that flows out from the communication hole and undergoes adiabatic expansion radially outward and introduces it into the expanded space.

3. The second on-off valve has a cylindrical portion (41) that is slidable against the inner circumferential surface of the main body, and the expansion space is formed radially outward of the cylindrical portion. The gas fuel injection valve according to claim 2, wherein the cylindrical portion has an opening (43) that communicates the expanded space with an inner space radially inside it.

4. A gas fuel injection valve (10) that directly injects gaseous fuel into the combustion chamber of an internal combustion engine, It comprises a cylindrical body (11, 12) having a fuel passage inside and a nozzle (15) at its tip, The main body has a partition (33) that divides the fuel passage into an upstream first fuel passage (P1) and a downstream second fuel passage (P2), and the partition is provided with a communication hole (34) that connects the first fuel passage and the second fuel passage. The main body is provided with a first on-off valve (13) that opens and closes the communication hole from the first fuel passage side, a second on-off valve (14) that opens and closes the communication hole from the second fuel passage side, and a sealing member (27) that seals the area around the opening of the communication hole between the first on-off valve and the compartment. The first on-off valve is driven to open by the drive unit (25), while the second on-off valve opens when the pressure in the communication hole becomes higher than the biasing force of the biasing member (45) that biases the second on-off valve to the closed side. The system has a configuration in which the gas fuel that flows out from the communication hole and undergoes adiabatic expansion upon opening of the second on-off valve collides with the extensions (35, 38) that extend downstream from the compartment, thereby cooling the extensions. The main body portion extends downstream from the outer periphery of the partition portion and has a peripheral wall portion (35) that forms the second fuel passage, and the peripheral wall portion is the extension portion. The second on-off valve has a guide portion (42) that guides the gas fuel that flows out from the communication hole and undergoes adiabatic expansion radially outward and causes it to collide with the circumferential wall, and also has a cylindrical portion (41) that is slidable against the inner circumferential surface of the main body, In the main body, the diameter of the second fuel passage differs between the uppermost portion and its downstream side, and the passage diameter is expanded in the uppermost portion, thereby forming an annular expansion space (S1) on the radially outer side of the cylindrical portion. The guide portion of the second on-off valve guides the gas fuel that flows out from the communication hole and undergoes adiabatic expansion radially outward, and introduces it into the expanded space. The cylindrical portion has an opening (43) that connects the expanded space with an inner space radially inside it, and is a gas fuel injection valve.

5. The gas fuel injection valve according to any one of claims 2 to 4, wherein the expanded space is provided with a biasing member (45) that biases the second on-off valve to the closed side.

6. A gas fuel injection valve (10) that directly injects gaseous fuel into the combustion chamber of an internal combustion engine, It comprises a cylindrical body (11, 12) having a fuel passage inside and a nozzle (15) at its tip, The main body has a partition (33) that divides the fuel passage into an upstream first fuel passage (P1) and a downstream second fuel passage (P2), and the partition is provided with a communication hole (34) that connects the first fuel passage and the second fuel passage. The main body is provided with a first on-off valve (13) that opens and closes the communication hole from the first fuel passage side, a second on-off valve (14) that opens and closes the communication hole from the second fuel passage side, and a sealing member (27) that seals the area around the opening of the communication hole between the first on-off valve and the compartment. The first on-off valve is driven to open by the drive unit (25), while the second on-off valve opens when the pressure in the communication hole becomes higher than the biasing force of the biasing member (45) that biases the second on-off valve to the closed side. The system has a configuration in which the gas fuel that flows out from the communication hole and undergoes adiabatic expansion upon opening of the second on-off valve collides with the extensions (35, 38) that extend downstream from the compartment, thereby cooling the extensions. A gas fuel injection valve in which the total volume of the communication hole provided in the compartment is the volume of residual gas remaining downstream of the first on-off valve after the first on-off valve has been closed and before the first on-off valve is opened again.

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