fuel injection device

Abstract

To decrease a thermal load to a hydrogen injector for direct injection due to a combustion gas, and to suppress a decrease in durability of the hydrogen injector for direct injection.SOLUTION: A fuel injection device 28 includes a hydrogen injector 30a for direct injection which injects a hydrogen gas. At least a part of the hydrogen injector 30a for direct injection is arranged outside of a cylinder head of a hydrogen engine 10. A cylinder jet flow pipe 50 is provided for guiding the hydrogen gas injected from the hydrogen injector 30a for direct injection into a cylinder of the hydrogen engine 10. An outer opening valve 60 is provided on a downstream side of the cylinder jet flow pipe 50. The outer opening valve 60 is closed normally, and is opened at the time of an increase in pressure inside the cylinder jet flow pipe 50 during opening of a valve in the hydrogen injector 30a for direct injection.SELECTED DRAWING: Figure 1

Description

[[Technical Field]]

[0001] The present invention relates to a fuel injection device. [[Background Art]]

[0002] Conventionally, there is a direct-injection gasoline injector that injects gasoline into the cylinder of a gasoline engine (see Patent Document 1). There is also a direct injection (also called "direct injection type") fuel injection device provided with a direct injection gasoline injector (see Patent Document 2). Further, there is a fuel injection device including a port gasoline injection valve that injects gasoline into an intake port of an engine, and a direct-injection hydrogen injector that injects hydrogen gas into a cylinder (see Patent Document 3). [[Prior Art Documents]] [[Patent Documents]]

[0003] [[Patent Document 1]] Japanese Unexamined Patent Application Publication No. 2009-114865 (Paragraph

[0001] , Figure 1, Figure 9A) [[Patent Document 2]] Japanese Unexamined Patent Application Publication No. 2007-100547 (Paragraph

[0014] , Figure 1, Figure 2) [[Patent Document 3]] Japanese Unexamined Patent Application Publication No. 2004-76679 (Paragraph

[0022] , Figure 1, Figure 2) [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0004] According to Patent Documents 1 and 2, the nozzle at the tip of a direct-injection gasoline injector opens into the engine cylinder (combustion chamber), and gasoline is injected directly into the cylinder from the injector. With a direct-injection gasoline injector, the gasoline (liquid fuel) flowing inside the injector can be expected to provide cooling and lubrication to the sliding parts of the injector. Furthermore, the nozzle of the injector is composed of a metal valve seat member and a metal valve body that seats on and separates from the valve seat member, and when the valve is closed, the sealing performance of the nozzle is ensured by metal-to-metal contact between the valve seat member and the valve body (see Patent Document 1). This sealing performance of the nozzle by metal-to-metal contact between the valve seat member and the valve body (hereinafter referred to as "nozzle sealing performance") is ensured by the lubrication effect of gasoline. Therefore, there is no particular problem even if the nozzle of the direct-injection gasoline injector is exposed to the high-temperature combustion gas inside the cylinder (hereinafter referred to as "combustion gas"). Furthermore, in direct-injection gasoline injectors, the nozzle is exposed to combustion gases, making it impossible to provide a rubber sealing member between the valve seat member and the valve body.

[0005] Furthermore, if, for example, a direct-injection gasoline injector having the structure of Patent Document 1 is used as a direct-injection hydrogen injector according to Reference Document 3, even if hydrogen gas (gaseous fuel) flows inside the injector, cooling and lubrication of the sliding parts of the injector cannot be expected. Moreover, since the nozzle of the direct-injection hydrogen injector is exposed to combustion gas, the heat load on the direct-injection hydrogen injector is large. As a result, wear on the sliding parts of the injector increases, and wear on the metal-to-metal contact part of the nozzle increases, reducing the sealing performance of the nozzle. Consequently, a decrease in the durability of the direct-injection hydrogen injector becomes a problem.

[0006] The problem that this invention aims to solve is to reduce the thermal load on a direct-injection hydrogen injector caused by combustion gases, thereby suppressing a decrease in the durability of the direct-injection hydrogen injector. [Means for solving the problem]

[0007] The aforementioned problems can be solved by the following means.

[0008] The first means is a fuel injection device comprising a direct-injection hydrogen injector for injecting hydrogen gas, wherein at least a portion of the direct-injection hydrogen injector is located outside the cylinder head of a hydrogen engine, and is provided with an in-cylinder jet pipe that guides the jet of hydrogen gas injected from the direct-injection hydrogen injector into the cylinder of the hydrogen engine, and is provided with an externally opening valve downstream of the in-cylinder jet pipe, the externally opening valve is normally closed, and opens when the direct-injection hydrogen injector is opened due to the pressure increase in the in-cylinder jet pipe, the fuel injection device.

[0009] According to the first method, by providing an in-cylinder jet pipe that guides the hydrogen gas jet injected from the direct-injection hydrogen injector into the cylinder of the hydrogen engine, the direct-injection hydrogen injector can be positioned away from the cylinder of the hydrogen engine. Furthermore, when the direct-injection hydrogen injector is open, an external valve located downstream of the in-cylinder jet pipe opens due to the pressure rise inside the in-cylinder jet pipe, and the hydrogen gas jet is injected into the cylinder of the hydrogen engine. Also, when the direct-injection hydrogen injector is closed, the external valve is closed, which suppresses the intrusion of combustion gases into the in-cylinder jet pipe as the hydrogen engine piston rises. Therefore, the heat load on the direct-injection hydrogen injector due to combustion gases can be reduced. This suppresses wear on the sliding parts of the direct-injection hydrogen injector as well as wear on the metal-to-metal contact parts of the nozzle. Thus, the heat load on the direct-injection hydrogen injector due to combustion gases can be reduced, and the decrease in the durability of the direct-injection hydrogen injector can be suppressed. This is effective in suppressing the decrease in durability of direct-injection hydrogen injectors, which cannot be relied upon for cooling or lubrication of sliding parts by hydrogen gas.

[0010] The second means is a fuel injection device that, in the first means, is equipped with a water injection injector for injecting water into the in-cylinder jet pipe.

[0011] In the second method, water injected from a water injection injector is mixed with a hydrogen gas jet in the in-cylinder jet pipe. Since the water is supplied as a liquid, it can create a gas-liquid mixture of hydrogen gas and water by creating flow turbulence in the in-cylinder jet pipe due to inertial force. This gas-liquid mixture is injected into the cylinder of the hydrogen engine. In addition, the latent heat of vaporization when water vaporizes lowers the compression end temperature, which can improve the filling efficiency of the intake air introduced into the cylinder. Consequently, the occurrence of knock can be further suppressed, and the compression ratio can be increased. Furthermore, since water is an inert gas, the combustion speed is slowed, allowing hydrogen gas to be burned at an appropriate combustion speed, and the amount of NOx emissions can be reduced.

[0012] The third means is a fuel injection system that, in the first or second means, includes a port injection hydrogen injector for injecting the hydrogen gas, at least a portion of the port injection hydrogen injector is located outside the cylinder head, and includes a port jet pipe that guides the jet of hydrogen gas injected from the port injection hydrogen injector to the intake port of the hydrogen engine.

[0013] According to the third method, efficient operation can be achieved by selecting a hydrogen injector (direct injection hydrogen injector and / or port injection hydrogen injector) that injects hydrogen gas according to the operating conditions of the hydrogen engine. Furthermore, by providing a port jet pipe that guides the hydrogen gas jet injected from the port injection hydrogen injector to the intake port of the hydrogen engine, the hydrogen gas jet can be injected closer to the combustion chamber. This makes it possible to achieve high output of the hydrogen engine while suppressing the occurrence of abnormal combustion in the hydrogen engine. [Effects of the Invention]

[0014] According to the fuel injection device of the present invention, the thermal load on the direct injection hydrogen injector due to combustion gas can be reduced, and the deterioration of the durability of the direct injection hydrogen injector can be suppressed. [Brief explanation of the drawing]

[0015] [Figure 1] It is a cross-sectional view showing the periphery of a fuel injection device for a hydrogen engine according to Embodiment 1. [Figure 2] It is a cross-sectional view showing a direct injection unit. [Figure 3] It is a cross-sectional view showing an outward-opening valve. [Figure 4] It is a cross-sectional view taken along the line IV-IV in FIG. 3. [Figure 5] It is a plan view showing a plate member. [Figure 6] It is a cross-sectional view showing the periphery of the tip end of an in-cylinder jet pipe. [Figure 7] It is a configuration diagram showing a fuel supply system. [Figure 8] It is a cross-sectional view showing a direct injection unit according to Embodiment 2. [Figure 9] It is a configuration diagram showing a fuel supply system. [Figure 10] It is a cross-sectional view showing the periphery of a fuel injection device for a hydrogen engine according to Embodiment 3. [Figure 11] It is a cross-sectional view showing the periphery of a fuel injection device for a hydrogen engine according to Embodiment 4. [Figure 12] It is a cross-sectional view showing a direct injection unit. [Figure 13] It is a cross-sectional view showing a port injection unit. [Figure 14] It is a diagram showing a hydrogen injection map. [Figure 15] It is a cross-sectional view showing the periphery of a fuel injection device for a hydrogen engine according to Embodiment 5. Mode for Carrying Out the Invention

[0016] Hereinafter, modes for carrying out the present invention will be described with reference to the drawings.

[0017] [Embodiment 1] The fuel injection system according to this embodiment is used in a hydrogen engine mounted on a vehicle such as an automobile. The hydrogen engine is a multi-cylinder (e.g., 4-cylinder) reciprocating type spark-ignition hydrogen engine that uses hydrogen gas as fuel. Figure 1 is a cross-sectional view showing the peripheral part of the fuel injection system of the hydrogen engine.

[0018] (Hydrogen engine) As shown in Figure 1, the hydrogen engine 10 has a cylinder block 11 and a cylinder head 12. A piston 13 is arranged in each cylinder of the cylinder block 11. The cylinder block 11, cylinder head 12 and piston 13 form a combustion chamber 14. The cylinder head 12 has an intake port 16 and an exhaust port 18 that communicate with the combustion chamber 14. The cylinder head 12 is equipped with an intake valve 17 that opens and closes the downstream opening end of the intake port 16, and an exhaust valve 19 that opens and closes the upstream opening end of the exhaust port 18. The cylinder head 12 is equipped with a spark plug 21 located at the top of the combustion chamber 14.

[0019] (Fuel injection device) The fuel injection system 28 includes a direct injection unit 30. The direct injection unit 30 is integrally held in a housing (not shown) installed on the cylinder head 12.

[0020] (Direct injection unit 30) Figure 2 is a cross-sectional view showing the direct injection unit 30. As shown in Figure 2, the direct injection unit 30 includes a direct injection hydrogen injector 30a that injects hydrogen gas, an in-cylinder jet pipe 50 connected to the tip of the direct injection hydrogen injector 30a, and an outward-opening valve 60 provided on the downstream side (more specifically, the downstream end) of the in-cylinder jet pipe.

[0021] The direct injection hydrogen injector 30a has a solenoid valve structure. The direct injection hydrogen injector 30a comprises a core 31, an electromagnetic solenoid 32, a body 33, a valve body 35, a spring 37, and a seat 39. The core 31 is formed in a cylindrical shape from a magnetic material resistant to hydrogen embrittlement. An adjustment pipe 43 is press-fitted into the axial middle portion of the core 31. A strainer 44 is installed inside the upstream end of the core 31. A piping connection portion 30b is provided at the upstream end of the core 31.

[0022] The electromagnetic solenoid 32 is provided so as to surround the downstream end (lower end in Figure 2) of the core 31. The electromagnetic solenoid 32 has a bobbin 32a, a coil 32b, and a housing 32c. The bobbin 32a is fixed to the core 31. The coil 32b is wound around the bobbin 32a. The housing 32c is formed in a C-shape from a magnetic material. The bobbin 32a and coil 32b are housed inside the housing 32c.

[0023] The core 31, which includes the electromagnetic solenoid 32, is surrounded by a resin case 41. The case 41 has a connector 41a for connecting an external connector (not shown). Terminal pins 42 connected to the coil 32b are located on the connector 41a. The terminal pins 42 are electrically connected to a control unit (hereinafter referred to as "ECU") 48 (see Figure 1) via the external connector. The ECU 48 controls the operation of the direct injection hydrogen injector 30a (injection control), that is, the coil 32b is energized at the timing when hydrogen gas should be injected.

[0024] The body 33 is formed in a cylindrical shape from a magnetic material resistant to hydrogen embrittlement. The body 33 is concentrically positioned downstream of the core 31 (lower side in Figure 2). The body 33 is liquid-tightly connected to the core 31 via a sleeve 45 made of a non-magnetic material. The sleeve 45 is fitted to the outer circumference of the core 31 and fixed by welding, while it is fitted to the inner circumference of the body 33 and welded thereto. The upstream end of the body 33 is covered by a case 41.

[0025] The valve body 35 is positioned to be axially movable within the body 33. The valve body 35 is formed in a hollow cylindrical shape from a magnetic material resistant to hydrogen embrittlement. The hollow portion of the valve body 35 is in communication with the hollow portion of the core 31. An armature portion 35a is formed at the upstream end of the valve body 35.

[0026] A valve portion 35b is formed at the downstream end of the valve body 35 to close the open end of the valve body 35. The armature portion 35a and the valve portion 35b are concentrically connected by a cylindrical portion 35c. A communication hole 35d is formed in the cylindrical portion 35c, which penetrates radially at a position near the valve portion 35b. The inside and outside of the cylindrical portion 35c are in communication through the communication hole 35d. A circular recess is formed in the center of the tip surface of the valve portion 35b of the valve body 35. An elastic circular plate-shaped sealing member 36 is bonded to this recess by baking. The sealing member 36 is made of rubber. The sealing member 36 is baked onto the valve portion 35b such that the protrusion dimension relative to the tip surface of the valve portion 35b of the valve body 35 is a constant amount.

[0027] The spring 37 is interposed between the opposing surfaces of the valve body 35 and the adjustment pipe 43. The spring 37 is a coil spring. Due to the elasticity of the spring 37, the valve body 35 is biased downstream. The spring 37 and the adjustment pipe 43 are made of a metal material that is resistant to hydrogen embrittlement.

[0028] The seat 39 is fitted into the downstream end of the body 33 and fixed by welding. The seat 39 is made of a metal resistant to hydrogen embrittlement and is formed in a bottomed cylindrical shape, with the bottom seat portion 39a facing upstream. An injection hole 39b is formed in the seat portion 39a. The nozzle portion 40 is composed of the valve body 35 and the seat 39.

[0029] When the valve body 35 is closed, the sealing member 36 is compressed between the valve portion 35b and the seat portion 39a of the seat 39, thereby ensuring a seal between them. Furthermore, the outer circumference of the tip surface of the valve portion 35b and the outer circumference of the seat portion 39a of the seat 39 make metal-to-metal contact, which keeps the compression ratio of the sealing member 36 constant, thereby suppressing deformation of the sealing member 36. The seat 39 corresponds to the "valve seat member" as defined herein. The valve body 35 corresponds to the "valve body" as defined herein. The body 33 is also provided with an elastic annular sealing member 46. The sealing member 46 is made of rubber.

[0030] In the direct-injection hydrogen injector 30a, when the coil 32b of the electromagnetic solenoid 32 is not energized, the valve portion 35b seats on the seat portion 39a due to the biasing force of the spring 37, thereby closing the injection hole 39b in a sealed state. That is, with the compression ratio of the sealing member 36 kept constant by the metal-to-metal contact between the seat 39 and the valve body 35, the sealing member 36 is compressed between the valve portion 35b of the valve body 35 and the seat portion 39a of the seat 39, thereby creating an elastic seal between them. As a result, hydrogen gas is not injected from the injection hole 39b of the seat 39. In this state, hydrogen gas flows into the space defined by the valve body 35 and the body 33 through the core 31, the adjustment pipe 43 and the internal space of the valve body 35, and the communication hole 35d of the valve body 35.

[0031] Furthermore, when the coil 32b is energized, the valve body 35 is retracted against the biasing force of the spring 37, causing the seal member 36 and the valve portion 35b to separate, or become separated, from the seat portion 39a of the seat 39. This results in the injection hole 39b being opened, creating an open valve state. As a result, hydrogen gas is injected from the injection hole 39b in a high-speed jet. The hydrogen gas injection pressure of the direct injection hydrogen injector 30a is, for example, 0.5 to 1.0 MPa.

[0032] The electromagnetic solenoid 32 of the direct-injection hydrogen injector 30a is basically used in two positions, "open" and "closed," by switching the current supplied to the coil 32b on and off. In other words, the direct-injection hydrogen injector 30a controls the amount of hydrogen gas injected by changing the opening time and opening / closing timing of the electromagnetic solenoid 32. The ECU 48 (see Figure 1) performs duty cycle control by changing the duty cycle of the pulsed excitation current supplied to the coil 32b of the electromagnetic solenoid 32. The duty cycle is calculated by dividing the ON time of the pulsed excitation current by the switching period, which is the sum of the ON time and OFF time of the pulsed excitation current. The direct-injection hydrogen injector 30a injects hydrogen gas in a high-speed jet when it is activated by an injection signal input from the ECU 48.

[0033] The ECU48 is comprised of a central processing unit (CPU) that performs various processes related to engine control, a memory that stores control programs and information necessary for engine control, and a drive circuit for the direct injection hydrogen injector 30a. The ECU48 is connected to a crank sensor, accelerator sensor, knock sensor, air flow meter, coolant temperature sensor, etc., which detect the engine operating status. The ECU48 performs various engine controls, including injection control and ignition timing control, according to the operating status of the hydrogen engine 10 as determined by the detection signals of the various sensors.

[0034] (In-cylinder jet pipe 50) The in-cylinder jet pipe 50 is formed as a straight, cylindrical tube made of a metal material resistant to hydrogen embrittlement. A stepped cylindrical injector connection section 51 is concentrically formed at the base end (upstream end) of the in-cylinder jet pipe 50. The tip (hydrogen gas injection side end) of the direct injection hydrogen injector 30a is fitted into the injector connection section 51. The injector connection section 51 and the body 33 are elastically sealed by a sealing member 46.

[0035] A straight gas flow path 52 is formed inside the in-cylinder jet pipe 50 to guide the hydrogen gas jet injected from the direct injection hydrogen injector 30a into the cylinder of the hydrogen engine 10 (see Figure 1). At the upstream end of the gas flow path 52, a tapered section 52a is formed, which gradually increases in diameter from the downstream side to the upstream side. The tapered section 52a has a maximum diameter slightly smaller than the inner diameter of the cylindrical section of the seat 39. At the downstream end of the gas flow path 52, an outward-opening valve mounting section 52b is formed to increase the diameter. An elastic cylindrical seal ring 54 is fitted to the outer circumferential surface of the downstream end of the in-cylinder jet pipe 50. The seal ring 54 is made of Teflon resin (registered trademark).

[0036] (Outward-opening valve 60) The outward-opening valve 60 is provided on the outward-opening valve mounting portion 52b of the in-cylinder jet pipe 50. Figure 3 is a cross-sectional view showing the outward-opening valve 60, and Figure 4 is a cross-sectional view taken along the line IV-IV in Figure 3. As shown in Figure 3, the outward-opening valve 60 comprises a valve seat member 62, a valve member 64, a spring 66, and a plate member 68. The components of the outward-opening valve 60 (62, 64, 66, 68) are made of a metal material resistant to hydrogen embrittlement.

[0037] The valve seat member 62 is formed in the shape of a cap that closes the tip opening of the in-cylinder jet pipe 50. A circular nozzle 62a is formed in the center of the valve seat member 62. Downstream of the nozzle 62a, a tapered valve seat surface 62b is formed, with the diameter gradually increasing towards the downstream side.

[0038] The valve member 64 has a valve stem portion 64a, a neck portion 64b, a ball portion 64c, and a valve portion 64d. The valve stem portion 64a, the neck portion 64b, the ball portion 64c, and the valve portion 64d are formed on the same axis. The valve stem portion 64a has an outer diameter smaller than the diameter of the nozzle 62a of the valve seat member 62. The neck portion 64b is formed at the upstream end of the valve stem portion 64a and has an outer diameter smaller than the outer diameter of the valve stem portion 64a. The ball portion 64c is formed at the tip of the neck portion 64b and has an outer diameter approximately the same as the outer diameter of the valve stem portion 64a. The valve portion 64d is tapered at the downstream end of the valve stem portion 64a. The valve portion 64d has a tapered surface that can contact the valve seat surface 62b of the valve seat member 62. The valve member 64 is inserted through the nozzle 62a of the valve seat member 62. The spring 66 is a coil spring. The spring 66 is fitted onto the valve shaft portion 64a of the valve member 64. The spring 66 corresponds to the "elastic member" as defined herein.

[0039] The plate member 68 is formed in a disc shape. The plate member 68 has an outer diameter smaller than the inner diameter of the outward-opening valve mounting portion 52b of the in-cylinder jet pipe 50. Figure 5 is a plan view showing the plate member 68. As shown in Figure 5, a U-shaped slit groove 68a is formed in the plate member 68. A tapered engagement surface 68b is formed around the bottom of the slit groove 68a (see Figure 3). Multiple (seven shown in Figure 5) communication holes 68c are formed in the plate member 68. The communication holes 68c are arranged at equal intervals in the circumferential direction around the engagement surface 68b.

[0040] As shown in Figure 3, the plate member 68 has a slit groove 68a that engages with the neck portion 64b of the valve member 64. This positions the plate member 68 concentrically with the valve member 64 (see Figure 4). The assembly of the plate member 68 to the valve stem portion 64a holds the spring 66 in a compressed state between the valve seat member 62 and the plate member 68. Furthermore, the biasing force of the valve member 64 due to the elasticity of the spring 66 causes the valve portion 64d to contact the valve seat surface 62b of the valve seat member 62. The contact (metal-to-metal contact) between the valve portion 64d and the valve seat member 62 ensures a seal between them. In addition, the engaging surface 68b of the plate member 68 contacts the spherical portion 64c of the valve member 64. The outward-opening valve 60, which is assembled with a valve member 64, a spring 66, and a plate member 68 on a valve seat member 62, is attached to the in-cylinder jet pipe 50 by fixing the valve seat member 62 in a state where it is fitted into the outward-opening valve mounting portion 52b of the in-cylinder jet pipe 50.

[0041] (Installation of direct injection unit 30 on hydrogen engine 10) As shown in Figure 1, the in-cylinder jet pipe 50 of the direct injection unit 30 is inserted through a through hole 12a formed in the side wall portion 12b of the combustion chamber 14 in the cylinder head 12 of the hydrogen engine 10. As a result, at least a portion of the direct injection hydrogen injector 30a is located outside the cylinder head 12. The through hole 12a penetrates the side wall portion 12b. The in-cylinder jet pipe 50 is also provided so as to penetrate the side wall portion 12b of the cylinder head 12. Figure 6 is a cross-sectional view showing the peripheral portion of the tip of the in-cylinder jet pipe.

[0042] As shown in Figure 6, the outward-opening valve 60 is positioned close to the umbrella portion 17a of the intake valve 17 when it is closed. The seal ring 54 seals the space between the cylinder head 12 and the in-cylinder jet pipe 50.

[0043] The direct injection hydrogen injector 30a is controlled by the ECU48 (see Figure 1). The ECU48 is configured to operate the direct injection hydrogen injector 30a to inject hydrogen gas from the latter half of the intake stroke to the first half of the compression stroke of the hydrogen engine 10.

[0044] (Fuel supply system) Figure 7 is a diagram showing the fuel supply system. As shown in Figure 7, the fuel supply system 70 includes a hydrogen storage tank 71. Hydrogen gas is stored in the hydrogen storage tank 71 under high pressure. The piping connection part 30b (see Figure 1) of the direct injection hydrogen injector 30a of the direct injection unit 30 is connected to the hydrogen storage tank 71 via a hydrogen gas supply passage 72. A shut-off valve 73 and a pressure reducing valve 74 are provided in the middle of the hydrogen gas supply passage 72. The shut-off valve 73 is a solenoid valve that functions as the main valve for the hydrogen storage tank 71. When the shut-off valve 73 is opened, hydrogen gas is supplied from the hydrogen storage tank 71 to the hydrogen gas supply passage 72. The pressure reducing valve 74 is a pressure regulating valve that reduces the pressure of the hydrogen gas. The shut-off valve 73 is controlled to open and close by an ECU 48 (see Figure 1).

[0045] (Operation of direct injection unit 30) When hydrogen gas is not being injected from the direct-injection hydrogen injector 30a, i.e., under normal conditions, the outward-opening valve 60 is closed. That is, due to the elasticity of the spring 66, the valve portion 64d of the valve member 64 is in contact with the valve seat surface 62b of the valve seat member 62.

[0046] Hydrogen gas is injected when the direct injection hydrogen injector 30a is activated between the latter half of the intake stroke and the first half of the compression stroke of the hydrogen engine 10. As a result, the hydrogen injection pressure caused by the pressure increase in the gas passage 52 of the in-cylinder jet pipe 50 acts on the outer surface of the valve portion 64d of the valve member 64 of the out-open valve 60. This causes the valve member 64 to open against the elasticity of the spring 66 (see the dashed line 64d(64) in Figure 3). Therefore, the hydrogen gas jet injected from the direct injection hydrogen injector 30a is injected as a high-speed jet from the gas passage 52 of the in-cylinder jet pipe 50, through the communication hole 68c of the plate member 68 of the out-open valve 60, and into the combustion chamber 14 from the injection port 62a of the valve seat member 62. The hydrogen gas is burned in the combustion chamber 14 when the spark plug 21 is ignited at a predetermined timing. When the direct-injection hydrogen injector 30a stops operating, the valve member 64 of the outward-opening valve 60 is closed by the elasticity of the spring 66.

[0047] (Advantages of Embodiment 1) According to this embodiment, by providing an in-cylinder jet pipe 50 that guides the hydrogen gas jet injected from the direct-injection hydrogen injector 30a into the cylinder of the hydrogen engine 10, the direct-injection hydrogen injector 30a can be positioned away from the combustion chamber 14 (inside the cylinder) of the hydrogen engine 10. Furthermore, when the direct-injection hydrogen injector 30a is open, an external valve 60 provided downstream of the in-cylinder jet pipe 50 opens due to the pressure rise inside the in-cylinder jet pipe 50, and the hydrogen gas jet is injected into the cylinder of the hydrogen engine 10. Also, when the direct-injection hydrogen injector 30a is closed, the external valve 60 is closed, so that the intrusion of combustion gas into the in-cylinder jet pipe 50 due to the rise of the piston 13 of the hydrogen engine 10 can be suppressed.

[0048] Therefore, the heat load on the direct injection hydrogen injector 30a due to combustion gases can be reduced. This suppresses wear on the sliding parts of the direct injection hydrogen injector 30a (specifically, the sliding parts between the valve body 35 and the body 33 and sleeve 45). At the same time, wear on the metal-to-metal contact parts of the nozzle 40 (the contact parts between the seat 39 and the valve body 35) can be suppressed. Thus, the heat load on the direct injection hydrogen injector 30a due to combustion gases can be reduced, and a decrease in the durability of the direct injection hydrogen injector 30a can be suppressed. This is effective in suppressing a decrease in the durability of the direct injection hydrogen injector 30a, which cannot be relied upon for cooling and lubrication of sliding parts by hydrogen gas.

[0049] Furthermore, the valve member 64, which is the movable part of the outward-opening valve 60, can be made significantly lighter than the valve body 35 of the direct-injection hydrogen injector 30a. This reduces the impact force of the valve member 64 on the valve seat member 62 when the valve is closed, thereby suppressing wear on the metal-to-metal contact portion (the contact portion between the valve seat member 62 and the valve member 64). As a result, reliable sealing between the valve seat member 62 and the valve member 64 in the outward-opening valve 60, which is exposed to combustion gas, can be maintained over a long period of time. Consequently, the intrusion of combustion gas into the in-cylinder jet pipe 50 can be suppressed over a long period of time.

[0050] Furthermore, the seal ring 54 provided between the in-cylinder jet pipe 50 and the cylinder head 12 can suppress the intrusion of combustion gas between them. This suppresses the in-cylinder jet pipe 50 from sticking to the cylinder head 12 due to unburned oil components in the combustion gas, thereby preventing deterioration of the replacement workability of the direct injection unit 30. It also suppresses wear of the seal member 46 and improves durability. In addition, from the viewpoint of durability and reliability of the out-open valve 60, it is effective to provide the seal ring 54 near the out-open valve 60, but the position of the seal ring 54 should be set considering the heat resistance of the seal ring 54.

[0051] Furthermore, by connecting the in-cylinder jet pipe 50 to the tip of the direct-injection hydrogen injector 30a, the valve body 35 can be made smaller and lighter in the axial direction compared to conventional injectors (see Patent Document 1). Consequently, the spring pressure of the spring 37 can be reduced. This suppresses wear on the sliding parts of the direct-injection hydrogen injector 30a (specifically, the sliding parts between the valve body 35 and the body 33 and sleeve 45). In addition, the impact force of the valve body 35 on the seat 39 when closing the valve can be mitigated, and wear on the metal-to-metal contact parts (the contact parts between the seat 39 and the valve body 35) can be suppressed.

[0052] Furthermore, the cooperation between the in-cylinder jet pipe 50 and the seal ring 54 effectively reduces the heat load on the direct injection hydrogen injector 30a.

[0053] Furthermore, by mounting the direct injection hydrogen injector 30a upstream of the in-cylinder jet pipe 50, the heat load on the direct injection hydrogen injector 30a is reduced, allowing a rubber sealing member 36 to be provided on the valve portion 35b of the valve body 35, and suppressing the deterioration of the sealing member 36, thereby improving its durability. Additionally, by maintaining a constant compression ratio of the sealing member 36 through metal-to-metal contact between the seat 39 and the valve body 35, deterioration of the sealing member 36 is suppressed, further improving its durability. Therefore, reliable sealing performance by the sealing member 36 between the valve body 35 and the seat 39 of the nozzle portion 40 can be maintained over a long period of time.

[0054] Furthermore, since it is a fuel injection device 28 for an in-cylinder injection type hydrogen engine 10, it can suppress the occurrence of abnormal combustion in the hydrogen engine 10 while improving the efficiency of filling the cylinder with intake air, thereby enabling higher output for the hydrogen engine 10.

[0055] Furthermore, hydrogen gas is injected from the direct injection unit 30 during the latter half of the intake stroke to the first half of the compression stroke of the hydrogen engine 10. This allows the direct injection unit 30 to supply hydrogen gas at the same injection pressure level as the intake port injection.

[0056] Furthermore, when hydrogen gas is injected from the direct-injection hydrogen injector 30a, the high-speed jet of hydrogen gas diffuses 360° in a conical shape along the outer circumferential surface of the valve portion 64d of the valve member 64 of the outward-opening valve 60, thereby improving the mixing of hydrogen gas and air.

[0057] [Embodiment 2] This embodiment is a modification of Embodiment 1 (see Figures 1-7), so the modified parts will be described, and the same reference numerals will be used for the same parts as in Embodiment 1, and redundant explanations will be omitted. Figure 8 is a cross-sectional view showing the direct injection unit. As shown in Figure 8, the direct injection unit 130 is the direct injection unit 30 of Embodiment 1 (see Figure 2) with the addition of a water injection injector 130a that injects water into the in-cylinder jet pipe 50.

[0058] A negative pressure chamber 152c is formed upstream of the tapered section 52a of the in-cylinder jet pipe 50, increasing its diameter. An ejector 155 is positioned inside the negative pressure chamber 152c. The ejector 155 is formed in a tapered cylindrical shape, gradually decreasing in diameter from the upstream side to the downstream side. The ejector 155 uses the flow of hydrogen gas to draw in water injected from the water injection injector 130a and mixes the hydrogen gas with the water.

[0059] A water injection injector connection portion 156, which communicates with the negative pressure chamber 152c, is formed on the side wall of the negative pressure chamber 152c. The tip (water injection side end) of the water injection injector 130a is fitted into the water injection injector connection portion 156. The axis of the water injection injector connection portion 156 intersects (orthogonal in Figure 8) with the axis of the in-cylinder jet pipe 50.

[0060] (Water injection injector 130a) The water injection injector 130a has a solenoid valve structure. The basic configuration of the water injection injector 130a is substantially the same as the basic configuration of the direct injection hydrogen injector 30a (see Figure 2) of Embodiment 1. For this reason, in the water injection injector 130a, components and parts common to the direct injection hydrogen injector 30a are given a number in the 100s with the same last two digits, and their explanations are omitted.

[0061] The water injection injector 130a has a nozzle portion 140 with a different configuration from the nozzle portion 40 of Embodiment 1 (see Figure 2). The nozzle portion 140 consists of a valve body 135 and a seat 139. The valve body 135 has an armature member 135a, a valve member 135b, and a cylindrical member 135c. The armature member 135a is formed in a short cylindrical shape from a magnetic material. The armature member 135a is arranged to be axially movable within the upstream end of the body 133. The hollow portion of the armature member 135a is in communication with the hollow portion of the core 131.

[0062] The cylindrical member 135c is formed from a metal material into a hollow cylindrical shape. The upstream end of the cylindrical member 135c is concentrically connected to the armature member 135a by welding or the like. The cylindrical member 135c has an outer diameter smaller than the outer diameter of the armature member 135a. The hollow portion of the cylindrical member 135c is in communication with the hollow portion of the armature member 135a. A communication hole 135d is formed in the cylindrical member 135c that penetrates in the radial direction.

[0063] The valve member 135b is formed spherically from a metallic material. The valve member 135b is connected to the downstream end of the cylindrical member 135c by welding. The downstream open end of the cylindrical member 135c is closed by the valve member 135b. The seat 139 is fitted into the downstream end of the body 133 and fixed by welding. The seat 139 is made of metal and is formed in a bottomed cylindrical shape, with the bottom seat portion 139a facing downstream. Injection holes 139b are formed in the seat portion 139a. The core 131 and body 133 may also be made of a magnetic material that is not affected by hydrogen embrittlement.

[0064] In the water injection injector 130a, when the coil 132b of the electromagnetic solenoid 132 is not energized, the valve member 135b of the valve body 135 comes into contact with the seat portion 139a of the seat 139, i.e., it sits, resulting in a closed valve state due to the biasing force of the spring 137. Therefore, water is not injected from the injection hole 139b of the seat 139.

[0065] Furthermore, when the coil 132b is energized, the valve body 135 is retracted against the biasing force of the spring 137, causing the valve member 135b to separate from the seat portion 139a of the seat 139, resulting in an open valve state. As a result, water is injected from the injection hole 139b. The water injection pressure of the water injection injector 130a is, for example, 0.1 to 0.3 MPa. The water injection injector 130a is activated by an injection signal input from the ECU 48 (see Figure 1) and injects water in a jet stream.

[0066] (Fuel supply system) Figure 9 is a diagram showing the fuel supply system. As shown in Figure 9, the fuel supply system 170 is the same as the fuel supply system 70 in Embodiment 1 (see Figure 7) with a water storage tank 176 added. Water is stored in the water storage tank 176. The piping connection part 130b (see Figure 8) of the water injection injector 130a is connected to the water storage tank 176 via a water supply channel 177.

[0067] A water supply pump 178, consisting of an electric pump, is installed in the middle of the water supply channel 177. Driven by the water supply pump 178, water in the water storage tank 176 is pumped through the water supply channel 177 to the water injection injector 130a. The water supply pump 178 is driven and controlled by an ECU 48 (see Figure 1). The ECU 48 operates the water injection injector 130a to inject water during the period from the start of hydrogen gas injection from the direct injection hydrogen injector 30a until just before the end of injection.

[0068] (Operation of direct injection unit 130) During the latter half of the intake stroke to the first half of the compression stroke of the hydrogen engine 10, the direct injection hydrogen injector 30a is activated to inject hydrogen gas, and at the same time, the water injection injector 130a is activated during the period from the start of hydrogen gas injection by the direct injection hydrogen injector 30a until just before the end of injection. As a result, the hydrogen gas injected from the direct injection hydrogen injector 30a is injected towards the ejector 155. Using this flow of hydrogen gas, water injected from the water injection injector 130a is drawn in, and the hydrogen gas and water are mixed. This mixture of hydrogen gas and water, i.e., the gas-liquid mixture, is injected into the combustion chamber 14 as a high-speed jet from the in-cylinder jet pipe 50 through the out-open valve 60. When the gas-liquid mixture is compressed in the combustion chamber 14, the water completely turns into steam, which has the effect of lowering the temperature of the mixture, and when combustion is finished, it is discharged as steam.

[0069] (Advantages of Embodiment 2) According to this embodiment, water injected from the water injection injector 130a is mixed with a hydrogen gas jet in the in-cylinder jet pipe 50. Since the water is supplied as a liquid, it can generate a gas-liquid mixture of hydrogen gas and water while creating flow turbulence in the in-cylinder jet pipe 50 due to inertial force. This gas-liquid mixture is injected into the cylinder of the hydrogen engine 10 (see Figure 1). Furthermore, the latent heat of vaporization when water vaporizes lowers the compression end temperature, thereby improving the filling efficiency of the intake air introduced into the cylinder. Consequently, the occurrence of knock can be further suppressed, allowing the compression ratio to be increased. In addition, since water is an inert gas, the combustion speed is slowed, allowing hydrogen gas to be burned at an appropriate combustion speed, and the amount of NOx generated can be reduced.

[0070] Furthermore, the ejector 155 utilizes the flow of hydrogen gas to draw in water injected from the water injection injector 130a, and the hydrogen gas and water are mixed. This allows for a lower water injection pressure in the water injection injector 130a and improves the mixing of hydrogen gas and water. The ejector 155 can also be omitted.

[0071] [Embodiment 3] This embodiment is a modification of Embodiment 1 (see Figure 1), so the modified parts will be described, and the same reference numerals will be used for the same parts as in Embodiment 1, and redundant explanations will be omitted. Figure 10 is a cross-sectional view showing the peripheral part of the fuel injection device 28 of the hydrogen engine 10. As shown in Figure 10, in this embodiment, a direct injection unit 30 is arranged in place of the spark plug 21 (see Figure 1) in Embodiment 1. The in-cylinder jet pipe 50 of the direct injection unit 30 is inserted through a through hole 12d formed in the upper wall portion 12c of the combustion chamber 14 in the cylinder head 12 of the hydrogen engine 10. As a result, at least a part of the direct injection hydrogen injector 30a is located outside the cylinder head 12. The through hole 12d penetrates the upper wall portion 12c. The in-cylinder jet pipe 50 is also provided so as to penetrate the upper wall portion 12c of the cylinder head 12. In this case, one spark plug (not shown) is mounted on the intake side and one on the exhaust side. This embodiment also provides the same effects and benefits as Embodiment 1.

[0072] [Embodiment 4] This embodiment is a modification of Embodiment 1 (see Figures 1-7), so the modified parts will be described, and the same reference numerals will be used for the same parts as in Embodiment 1, and redundant explanations will be omitted. Figure 11 is a cross-sectional view showing the peripheral part of the fuel injection device 28 of the hydrogen engine 10. As shown in Figure 11, this embodiment is a multi-cylinder hydrogen engine 10 equipped with a dual injection system that includes a direct injection unit 30 that directly injects hydrogen gas into the cylinder and a port injection unit 230 that injects hydrogen gas into the intake port 16. The port injection unit 230 is integrally held in a housing (not shown) installed on the cylinder head 12.

[0073] The direct injection hydrogen injector 30a of the direct injection unit 30 is substantially the same as the direct injection hydrogen injector 30a of Embodiment 1 (see Figure 2). The in-cylinder jet pipe 50 has been partially modified. Specifically, as shown in Figure 12, in this embodiment, the tapered portion 52a (see Figure 2) of the gas flow path 52 of the in-cylinder jet pipe 50 of Embodiment 1 has been changed to a tapered portion 52d. The tapered portion 52d has a maximum diameter slightly larger than the outer diameter of the lower end portion 33a of the body 33 of the direct injection hydrogen injector 30a. A hollow cylindrical straight portion 52e is formed between the tapered portion 52d and the sealing member 46.

[0074] (Port injection unit 230) Figure 13 is a cross-sectional view showing the port injection unit 230. As shown in Figure 13, the port injection unit 230 comprises a port injection hydrogen injector 230a that injects hydrogen gas, and a port jet pipe 250 connected to the tip of the port injection hydrogen injector 230a. The port injection hydrogen injector 230a is the same as the direct injection hydrogen injector 30a (see Figure 12) in this embodiment. Therefore, in the port injection hydrogen injector 230a, components and parts common to the direct injection hydrogen injector 30a are denoted by the same reference numerals and their descriptions are omitted.

[0075] The port jet pipe 250 is formed as a straight, cylindrical tube made of a metal material resistant to hydrogen embrittlement. A stepped cylindrical injector connection section 251 is formed concentrically at the base end (upstream end) of the port jet pipe 250. The tip (hydrogen gas injection side end) of the port injection hydrogen injector 230a is fitted into the injector connection section 251. The injector connection section 251 and the body 33 of the port injection hydrogen injector 230a are elastically sealed by a sealing member 46.

[0076] A straight gas channel 252 is formed inside the port jet pipe 250, which guides the jet of hydrogen gas injected from the port injection hydrogen injector 230a into the intake port 16 (see Figure 11) of the hydrogen engine 10. At the upstream end of the gas channel 252, a gas channel 252, a tapered section 252d, and a straight section 252e are formed, similar to the gas channel 52, tapered section 52d, and straight section 52e of the in-cylinder jet pipe 50 (see Figure 12). The remaining pipe-shaped portion of the port jet pipe 250, excluding the injector connection section 251, has a smaller outer diameter than the remaining pipe-shaped portion of the in-cylinder jet pipe 50, excluding the injector connection section 51. An elastic cylindrical sealing member 256 is attached to the outer circumferential surface of the downstream end of the injector connection section 251. The sealing member 256 is made of rubber.

[0077] (Installation of port injection unit 230 for hydrogen engine 10) As shown in Figure 11, the port jet pipe 250 of the port injection unit 230 is inserted through a through hole 12f formed in the upper wall portion 12e of the intake port 16 in the cylinder head 12 of the hydrogen engine 10. As a result, at least a portion of the port injection hydrogen injector 230a is located outside the cylinder head 12. The lower end opening of the through hole 12f is located downstream of the intake port 16 than its upper end opening.

[0078] The port jet pipe 250 is provided so as to penetrate the upper wall portion 12e of the intake port 16. The downstream end (tip) of the port jet pipe 250 is positioned close to the downstream portion of the intake port 16, specifically to the umbrella portion 17a of the intake valve 17 when it is closed. Furthermore, a sealing member 256 seals the space between the cylinder head 12 and the port jet pipe 250. A branch passage 72a, which is branched from the hydrogen gas supply passage 72 (see Figure 7), is connected to the piping connection portion 30b of the port injection hydrogen injector 230a.

[0079] The ECU48 is configured to control the injection of hydrogen by direct injection hydrogen injector 30a and port injection hydrogen injector 230a based on an injection map. As shown in Figure 14, the injection map is configured so that characteristic curve L1 is obtained by operating the port injection hydrogen injector 230a in the light load region. Furthermore, in the medium load and high load regions, characteristic curve L2 is obtained by operating both the port injection hydrogen injector 230a and the direct injection hydrogen injector 30a.

[0080] (Advantages of Embodiment 4) According to this embodiment, efficient operation can be achieved by selecting a hydrogen injector (direct injection hydrogen injector 30a and / or port injection hydrogen injector 230a) that injects hydrogen gas according to the operating conditions of the hydrogen engine 10.

[0081] In other words, in the light load range, by selecting the port injection hydrogen injector 230a and injecting a jet of hydrogen gas into the intake port 16, the heterogeneity of the air-fuel mixture in the light load range can be improved. Specifically, the penetrating force of the hydrogen jet injected directly into the cylinder via the in-cylinder jet pipe 50 by the direct injection hydrogen injector 30a decays more quickly after injection compared to the spray penetrating force of a direct injection gasoline engine, which can leave challenges in achieving homogenization of the air-fuel mixture. In particular, in the light load range, the flow velocity at intake is slow and the turbulence intensity is low, so combustion deterioration due to heterogeneous air-fuel mixture becomes a problem. To address this problem, in the light load range, by injecting hydrogen gas injected from the port injection hydrogen injector 230a into the intake port 16 via the port jet pipe 250, the heterogeneity of the air-fuel mixture in the light load range can be improved.

[0082] Furthermore, in the medium and high load ranges, hydrogen gas injected from the port injection hydrogen injector 230a is supplied to the intake port 16 via the port jet pipe 250, while hydrogen gas injected from the direct injection hydrogen injector 30a is supplied to the cylinder via the in-cylinder jet pipe 50. This allows for improved charging efficiency, which is a benefit of direct injection hydrogen engines. Note that the selection of the direct injection hydrogen injector 30a and / or the port injection hydrogen injector 230a may be changed as appropriate.

[0083] Furthermore, by providing a port jet pipe 250 that guides the hydrogen gas jet injected from the port injection hydrogen injector 230a to the intake port 16 of the hydrogen engine 10, the hydrogen gas jet can be injected closer to the combustion chamber 14. This makes it possible to suppress the occurrence of abnormal combustion in the hydrogen engine 10 while achieving high output of the hydrogen engine 10.

[0084] [Embodiment 5] This embodiment is a modification of Embodiment 4 (see Figure 11), so the modified parts will be described, and the same reference numerals will be used for the same parts as in Embodiment 4, and redundant explanations will be omitted. Figure 15 is a cross-sectional view showing the area around the fuel injection device 28 of the hydrogen engine 10. As shown in Figure 15, in this embodiment, similar to Embodiment 3 (see Figure 10), a direct injection unit 30 is arranged in place of the spark plug 21 (see Figure 11) in Embodiment 4. The same operation and effects as in Embodiment 4 can be obtained with this embodiment as well.

[0085] [Other embodiments] The present invention is not limited to the embodiments described above, and modifications are possible without departing from the present invention. For example, the present invention may be applied not only to vehicles such as automobiles, but also to aircraft, ships, and other hydrogen engine fuel injection systems. Furthermore, the outward-opening valve 60 may be provided not only at the downstream end of the in-cylinder jet pipe 50, but also upstream of that downstream end. [Explanation of Symbols]

[0086] 10 Hydrogen engine 12 Cylinder head 14. Combustion chamber (inside the cylinder) 16 intake ports 28 Fuel injection system 30 Direct injection unit 30a Hydrogen injector for direct injection 50 In-cylinder jet pipe 60 Outward-opening valve 130 Direct Injection Unit 130a Water Injector 230-port injection unit 230a Hydrogen injector for port injection 250-port jet pipe

Claims

1. A fuel injection system equipped with a direct-injection hydrogen injector that injects hydrogen gas, At least a portion of the hydrogen injector for direct injection is located outside the cylinder head of the hydrogen engine. The hydrogen engine is equipped with an in-cylinder jet pipe that guides the hydrogen gas jet injected from the direct-injection hydrogen injector into the cylinder. An externally opening valve is provided at the downstream end of the aforementioned in-cylinder jet pipe. The externally opening valve comprises a valve seat member having an injection port, a valve member for opening and closing the injection port, and an elastic member for biasing the valve member in the closing direction. Normally, the valve member is closed by the elasticity of the elastic member, and when the direct injection hydrogen injector is opened, the valve member is opened against the elasticity of the elastic member due to the pressure increase in the in-cylinder jet pipe. A fuel injection device in which the outward-opening valve is assembled to the in-cylinder jet pipe by attaching the valve seat member to the downstream end of the in-cylinder jet pipe.

2. A fuel injection device according to claim 1, A fuel injection device comprising a water injection injector for injecting water into the in-cylinder jet pipe.

3. A fuel injection device according to claim 1 or 2, It is equipped with a hydrogen injector for port injection that injects the aforementioned hydrogen gas, At least a portion of the aforementioned hydrogen injector for port injection is located outside the cylinder head, A fuel injection system comprising a port jet pipe that guides the jet of hydrogen gas injected from the port injection hydrogen injector to the intake port of the hydrogen engine.

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