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 gasoline injector for direct injection that injects gasoline into the cylinder of a gasoline engine (see Patent Document 1). Further, there is an in-cylinder injection type (also called "direct injection type") fuel injection device including a gasoline injector for direct injection (see Patent Document 2). Further, there is a fuel injection device including a port gasoline injection valve that injects gasoline into the intake port of an engine and a direct injection hydrogen injector that injects hydrogen gas into the cylinder (see Patent Document 3).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

[0001] , FIGS. 1, 9A)

Patent Document 2

[0014] , FIGS. 1, 2)

Patent Document 3

[0022] , FIGS. 1, 2)

Summary of the Invention

Problems to be Solved by the Invention

[0004] According to Patent Documents 1 and 2, the nozzle portion at the tip of the gasoline injector for direct injection opens into the cylinder (combustion chamber) of the engine, and gasoline is directly injected into the cylinder from the injector. According to the gasoline injector for direct injection, the cooling action of the injector and the lubricating action of the sliding portion can be expected by the gasoline (liquid fuel) flowing inside the injector. Further, the nozzle portion of the injector is composed of a metal valve seat member and a metal valve body that seats and unseats on the valve seat member, and the sealing property of the nozzle portion is ensured by the metal touch between the valve seat member and the valve body when the valve is closed (see Patent Document 1). The sealing property (hereinafter referred to as "the sealing property of the nozzle portion") of the nozzle portion by the metal touch between the valve seat member and the valve body is ensured by the lubricating action by gasoline. Therefore, there is no particular problem even if the nozzle portion of the gasoline injector for direct injection is exposed to the high-temperature combustion gas (hereinafter referred to as "combustion gas") inside the cylinder. In the gasoline injector for direct injection, since the nozzle portion is exposed to the combustion gas, a rubber sealing member cannot be provided between the valve seat member and the valve body.

[0005] Further, for example, when a gasoline injector for direct injection having the structure of Patent Document 1 is used as the hydrogen injector for direct injection of Cited Document 3, even if hydrogen gas (gaseous fuel) flows inside the injector, the cooling action of the injector and the lubricating action of the sliding portion cannot be expected. Further, since the nozzle portion of the hydrogen injector for direct injection is exposed to the combustion gas, the heat load on the hydrogen injector for direct injection is large. For this reason, the wear of the sliding portion of the injector increases, and the wear of the metal touch portion of the nozzle portion increases, resulting in a decrease in the sealing property of the nozzle portion. Therefore, a problem arises in that the durability of the hydrogen injector for direct injection decreases.

[0006] The problem to be solved by the present invention is to reduce the heat load on the hydrogen injector for direct injection due to the combustion gas and suppress the decrease in the durability of the hydrogen injector for direct injection.

Means for Solving the Problem

[0007] The above-described problem can be solved by the following means.

[0008] The first means is a fuel injection device including a direct injection hydrogen injector that injects hydrogen gas, at least a part of the direct injection hydrogen injector being disposed outside a cylinder head of a hydrogen engine, and including an in-cylinder jet pipe that guides a jet of the hydrogen gas injected from the direct injection hydrogen injector into the cylinder of the hydrogen engine, an outward-opening valve being provided on a downstream side of the in-cylinder jet pipe, the outward-opening valve being normally closed and being opened by a pressure increase in the in-cylinder jet pipe when the direct injection hydrogen injector is opened, which is a fuel injection device.

[0009] According to the first means, by including the in-cylinder jet pipe that guides the jet of the hydrogen gas injected from the direct injection hydrogen injector into the cylinder of the hydrogen engine, the direct injection hydrogen injector can be disposed at a position away from the inside of the cylinder of the hydrogen engine. Further, when the direct injection hydrogen injector is opened, the outward-opening valve provided on the downstream side of the in-cylinder jet pipe is opened by a pressure increase in the in-cylinder jet pipe, and the jet of the hydrogen gas is injected into the cylinder of the hydrogen engine. Further, when the direct injection hydrogen injector is closed, since the outward-opening valve is closed, it is possible to suppress the intrusion of the combustion gas into the in-cylinder jet pipe as the piston of the hydrogen engine rises. Therefore, the heat load on the direct injection hydrogen injector due to the combustion gas can be reduced. Thereby, wear of the sliding portion of the direct injection hydrogen injector can be suppressed, and wear of the metal touch portion of the nozzle portion can be suppressed. Thus, the heat load on the direct injection hydrogen injector due to the combustion gas can be reduced, and a decrease in the durability of the direct injection hydrogen injector can be suppressed. This is effective in suppressing a decrease in the durability of the direct injection hydrogen injector for which a cooling action by hydrogen gas and a lubricating action of the sliding portion cannot be expected.

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

[0011] According to the second means, the water injected from the water injector for water injection is mixed with the jet of hydrogen gas in the jet pipe for the cylinder. Since water is supplied as a liquid, an inertial force can create turbulence in the flow in the jet pipe for the cylinder and generate a gas-liquid mixture of hydrogen gas and water. This gas-liquid mixture is injected into the cylinder of the hydrogen engine. Further, due to the latent heat of vaporization when water vaporizes, the temperature at the compression end is lowered, so that the filling efficiency of the intake air introduced into the cylinder can be improved. As a result, the occurrence of knocking can be further suppressed, so that the compression ratio can be increased. Also, since water is an inert gas, the combustion speed becomes slow, and the amount of NOx generated can be reduced, enabling hydrogen gas to be burned at an appropriate combustion speed.

[0012] The third means is a fuel injection device provided with a hydrogen injector for port injection that injects the hydrogen gas in the first or second means, at least a part of the hydrogen injector for port injection being disposed outside the cylinder head, and including a jet pipe for ports that guides the jet of hydrogen gas injected from the hydrogen injector for port injection to the intake port of the hydrogen engine.

[0013] According to the third means, by selecting a hydrogen injector (direct injection hydrogen injector and / or hydrogen injector for port injection) that injects hydrogen gas according to the operating conditions of the hydrogen engine, efficient operation can be performed. Also, by including a jet pipe for ports that guides the jet of hydrogen gas injected from the hydrogen injector for port injection to the intake port of the hydrogen engine, the jet of hydrogen gas can be injected near the combustion chamber. Thereby, while suppressing the occurrence of abnormal combustion in the hydrogen engine, it is possible to achieve higher output of the hydrogen engine.

Advantages of the Invention

[0014] According to the fuel injection device of the present invention, the heat load on the direct injection hydrogen injector due to combustion gas can be reduced, and a decrease in the durability of the direct injection hydrogen injector can be suppressed.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Mode for Carrying Out the Invention

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

[0017] [Embodiment 1] The fuel injection device according to this embodiment is used for a hydrogen engine mounted on a vehicle such as an automobile. The hydrogen engine is a reciprocating spark-ignition hydrogen engine with multiple cylinders (for example, four cylinders) using hydrogen gas as fuel. FIG. 1 is a cross-sectional view showing the periphery of the fuel injection device of the hydrogen engine.

[0018] (Hydrogen Engine) As shown in FIG. 1, the hydrogen engine 10 has a cylinder block 11 and a cylinder head 12. A piston 13 is disposed in each cylinder of the cylinder block 11. A combustion chamber 14 is formed by the cylinder block 11, the cylinder head 12, and the piston 13. An intake port 16 and an exhaust port 18 communicating with the combustion chamber 14 are formed in the cylinder head 12. An intake valve 17 for opening and closing the downstream opening end of the intake port 16 and an exhaust valve 19 for opening and closing the upstream opening end of the exhaust port 18 are disposed in the cylinder head 12. A spark plug 21 located at the top of the combustion chamber 14 is disposed in the cylinder head 12.

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

[0020] (Direct Injection Unit 30) FIG. 2 is a cross-sectional view showing the direct injection unit 30. As shown in FIG. 2, the direct injection unit 30 includes a direct injection hydrogen injector 30a for injecting hydrogen gas, an in-cylinder jet pipe 50 connected to the tip of the direct injection hydrogen injector 30a, and an external opening valve 60 provided on the downstream side (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 includes 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 that is resistant to hydrogen embrittlement. An adjustment pipe 43 is press-fitted to an intermediate portion in the axial direction of the core 31. A strainer 44 is attached inside the upstream end of the core 31. A pipe 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 portion (the lower end portion in FIG. 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-shaped cylindrical form from a magnetic material. The bobbin 32a and the coil 32b are accommodated inside the housing 32c.

[0023] The periphery of the core 31 including the electromagnetic solenoid 32 is covered by a resin case 41. A connector 41a for connecting an external connector (not shown) is formed on the case 41. A terminal pin 42 connected to the coil 32b is arranged on the connector 41a. The terminal pin 42 is electrically connected to a control device (hereinafter referred to as "ECU") 48 (see FIG. 1) via the external connector. The operation of the direct injection hydrogen injector 30a is controlled (injection control) by the ECU 48, 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 that is resistant to hydrogen embrittlement. The body 33 is arranged concentrically on the downstream side (the lower side in FIG. 2) of the core 31. 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 on the outer peripheral side of the core 31 and fixed by welding, while being fitted and welded on the inner peripheral side of the body 33. The upstream end of the body 33 is covered by the case 41.

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

[0026] At the downstream end of the valve body 35, a valve portion 35b that closes the opening end of the valve body 35 is formed. The armature portion 35a and the valve portion 35b are concentrically connected by a cylindrical portion 35c. In the cylindrical portion 35c, a communication hole 35d that penetrates in the radial direction is formed at a position closer to the valve portion 35b. The inside and outside of the cylindrical portion 35c are communicated by the communication hole 35d. A circular recess is formed at the center of the tip surface of the valve portion 35b of the valve body 35. An elastic circular plate-shaped seal member 36 is adhered to the recess by baking. The seal member 36 is made of rubber. The seal member 36 is baked onto the valve portion 35b so that the protruding dimension with respect to the tip surface of the valve portion 35b of the valve body 35 becomes a certain 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 formed of a metal material that is resistant to hydrogen embrittlement.

[0028] The seat 39 is fitted and fixed by welding within the downstream end of the body 33. The seat 39 is made of a metal that is resistant to hydrogen embrittlement and is formed in a bottomed cylindrical shape, and the seat portion 39a on the bottom side is arranged facing upstream. Injection holes 39b are formed in the seat portion 39a. A nozzle portion 40 is constituted by the valve body 35 and the seat 39.

[0029] When the valve body 35 closes, the sealing member 36 is compressed between the valve portion 35b and the seat portion 39a of the seat 39, thereby ensuring the sealing performance between the two. Further, when the outer peripheral portion of the tip surface of the valve portion 35b and the outer peripheral portion of the seat portion 39a of the seat 39 are in metal contact, as a result, the compression rate of the sealing member 36 is kept constant, and thus the sagging of the sealing member 36 can be suppressed. The seat 39 corresponds to the "valve seat member" as referred to in this specification. The valve body 35 corresponds to the "valve body" as referred to in this specification. Further, an annular sealing member 46 having elasticity is provided on the body 33. 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 de-energized, due to the biasing of the spring 37, the valve portion 35b seats on the seat portion 39a, and thus the injection hole 39b is closed in a sealed state, i.e., a valve closed state. That is, with the compression rate of the sealing member 36 kept constant by the 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, and thus the two are elastically sealed. For this reason, hydrogen gas is not injected from the injection hole 39b of the seat 39. In this state, hydrogen gas flows into the space portion defined by the valve body 35 and the body 33 through the core 31, the adjustment pipe 43, the internal space of the valve body 35, and the communication hole 35d of the valve body 35.

[0031] Further, when the coil 32b is energized, the valve body 35 is retracted against the biasing of the spring 37, so that the sealing member 36 and the valve portion 35b are separated from, i.e., lifted off from, the seat portion 39a of the seat 39. Thereby, the injection hole 39b is opened to a valve open state. For this reason, hydrogen gas is injected from the injection hole 39b as 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 turning the current supplied to the coil 32b on and off. That is, the direct injection hydrogen injector 30a controls the injection amount of hydrogen gas by changing the opening time and the opening / closing timing of the electromagnetic solenoid 32. The ECU 48 (see FIG. 1) performs duty control to change the duty ratio of the pulsed excitation current supplied to the coil 32b of the electromagnetic solenoid 32. Note that the duty ratio is obtained by dividing the ON time of the pulsed excitation current by the switching period obtained by adding the ON time and the OFF time of the pulsed excitation current. The direct injection hydrogen injector 30a injects hydrogen gas in a high-speed jet by operating in response to the input of an injection signal from the ECU 48.

[0033] The ECU 48 is configured to include 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, a drive circuit for the direct injection hydrogen injector 30a, and the like. Connected to the ECU 48 are a crank sensor, an accelerator sensor, a knock sensor, an air flow meter, a coolant temperature sensor, etc., which detect the engine operating state. The ECU 48 performs various engine controls, including injection control and ignition timing control, according to the operating condition of the hydrogen engine 10 grasped by the detection signals of various sensors.

[0034] (In-cylinder jet pipe 50) The in-cylinder jet pipe 50 is formed in a circular tubular shape that extends linearly using a metal material resistant to hydrogen embrittlement. At the base end portion (upstream end portion) of the in-cylinder jet pipe 50, a stepped cylindrical injector connection portion 51 is formed concentrically. The tip portion (hydrogen gas injection side end portion) of the direct injection hydrogen injector 30a is fitted into the injector connection portion 51. The seal member 46 elastically seals the space between the injector connection portion 51 and the body 33.

[0035] Inside the in-cylinder jet pipe 50, a linear gas flow path 52 is formed to guide the jet of hydrogen gas injected from the direct injection hydrogen injector 30a into the cylinder of the hydrogen engine 10 (see FIG. 1). At the upstream end of the gas flow path 52, a tapered portion 52a is formed that gradually increases in diameter from the downstream side toward the upstream side. The tapered portion 52a has a maximum diameter that is slightly smaller than the inner diameter of the cylindrical portion of the sheet 39. At the downstream end of the gas flow path 52, an outward-opening valve mounting portion 52b that increases in diameter is formed. An elastic cylindrical seal ring 54 is mounted on the outer peripheral 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 in the outward-opening valve mounting portion 52b of the in-cylinder jet pipe 50. FIG. 3 is a cross-sectional view showing the outward-opening valve 60, and FIG. 4 is a cross-sectional view taken along the line IV-IV of FIG. 3. As shown in FIG. 3, the outward-opening valve 60 includes a valve seat member 62, a valve member 64, a spring 66, and a plate member 68. The constituent members (62, 64, 66, 68) of the outward-opening valve 60 are formed of a metal material that is resistant to hydrogen embrittlement.

[0037] The valve seat member 62 is formed in a cap shape that closes the tip opening of the in-cylinder jet pipe 50. A jet port 62a formed of a circular hole is formed in the central portion of the valve seat member 62. A tapered hole-shaped valve seat surface 62b that gradually increases in diameter toward the downstream is formed on the downstream side of the jet port 62a.

[0038] The valve member 64 has a valve shaft portion 64a, a neck portion 64b, a spherical portion 64c, and a valve portion 64d. The valve shaft portion 64a, the neck portion 64b, the spherical portion 64c, and the valve portion 64d are formed on the same axis. The valve shaft portion 64a has an outer diameter smaller than the diameter of the injection port 62a of the valve seat member 62. The neck portion 64b is formed at the upstream end of the valve shaft portion 64a and has an outer diameter smaller than that of the valve shaft portion 64a. The spherical portion 64c is formed at the tip of the neck portion 64b and has an outer diameter substantially equal to that of the valve shaft portion 64a. The valve portion 64d is formed in a tapered shape at the downstream end of the valve shaft 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 into the injection port 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" referred to in this specification.

[0039] The plate member 68 is formed in a disk shape. The plate member 68 has an outer diameter smaller than the inner diameter of the outer opening valve mounting portion 52b of the in-cylinder jet pipe 50. FIG. 5 is a plan view showing the plate member 68. As shown in FIG. 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 FIG. 3). A plurality (seven are shown in FIG. 5) of 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 FIG. 3, in the plate member 68, a slit groove 68a is engaged with a neck portion 64b of the valve member 64. Thereby, the plate member 68 is arranged concentrically with the valve member 64 (see FIG. 4). By assembling the plate member 68 to the valve shaft portion 64a, a spring 66 is held in a compressed state between the valve seat member 62 and the plate member 68. Further, due to the biasing of the valve member 64 by the elasticity of the spring 66, a valve portion 64d is brought into contact with a valve seat surface 62b of the valve seat member 62. The sealing performance between the two is ensured by the contact (metal touch) between the valve portion 64d and the valve seat member 62. Further, an engagement surface 68b of the plate member 68 is brought into contact with a spherical portion 64c of the valve member 64. The outward-opening valve 60, in which the valve member 64, the spring 66, and the plate member 68 are assembled to the valve seat member 62, is attached to the in-cylinder jet pipe 50 by being fixed in a state where the valve seat member 62 is fitted into an outward-opening valve mounting portion 52b of the in-cylinder jet pipe 50.

[0041] (Installation of the direct injection unit 30 for the hydrogen engine 10) As shown in FIG. 1, the in-cylinder jet pipe 50 of the direct injection unit 30 is inserted into an insertion hole 12a formed in a side wall portion 12b of a combustion chamber 14 in a cylinder head 12 of the hydrogen engine 10. Thereby, at least a part of the direct injection hydrogen injector 30a is arranged outside the cylinder head 12. The insertion hole 12a penetrates the side wall portion 12b. Further, the in-cylinder jet pipe 50 is provided so as to penetrate the side wall portion 12b of the cylinder head 12. FIG. 6 is a cross-sectional view showing a peripheral portion of a tip end portion of the in-cylinder jet pipe.

[0042] As shown in FIG. 6, the outward-opening valve 60 is arranged at a position close to an umbrella portion 17a of an intake valve 17 in a closed valve state. A seal ring 54 seals between the cylinder head 12 and the in-cylinder jet pipe 50.

[0043] The direct injection hydrogen injector 30a is injection-controlled by the ECU 48 (see FIG. 1). The ECU 48 is set to operate the direct injection hydrogen injector 30a so as to inject hydrogen gas during the latter half of the intake stroke to the first half of the compression stroke of the hydrogen engine 10.

[0044] (Fuel supply system) FIG. 7 is a configuration diagram showing the fuel supply system. As shown in FIG. 7, the fuel supply system 70 includes a hydrogen storage tank 71. Hydrogen gas is stored in the hydrogen storage tank 71 in a high-pressure state. A piping connection portion 30b (see FIG. 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 an electromagnetic valve that functions as a main valve of 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 the ECU 48 (see FIG. 1).

[0045] (Operation of the direct injection unit 30) When hydrogen gas is not injected from the direct injection hydrogen injector 30a, that is, normally, the normally open 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] The direct injection hydrogen injector 30a is operated from the latter half of the intake stroke to the first half of the compression stroke of the hydrogen engine 10, whereby hydrogen gas is injected. Then, the hydrogen injection pressure due to the pressure rise in the gas flow path 52 of the in-cylinder jet pipe 50 acts on the outer peripheral surface of the valve portion 64d of the valve member 64 of the out-opening valve 60. As a result, the valve member 64 is opened against the elasticity of the spring 66 (see the two-dot chain line 64d(64) in FIG. 3). Therefore, the jet of hydrogen gas injected from the direct injection hydrogen injector 30a passes from the gas flow path 52 of the in-cylinder jet pipe 50 through the communication hole 68c of the plate member 68 of the out-opening valve 60 and is injected into the combustion chamber 14 at a high speed jet from the injection port 62a of the valve seat member 62. The hydrogen gas is combusted when the ignition plug 21 is ignited at a predetermined timing in the combustion chamber 14. When the operation of the direct injection hydrogen injector 30a stops, the valve member 64 of the out-opening valve 60 is closed by the elasticity of the spring 66.

[0047] (Advantages of Embodiment 1) According to the present embodiment, by providing the in-cylinder jet pipe 50 that guides the jet of hydrogen gas injected from the direct injection hydrogen injector 30a into the cylinder of the hydrogen engine 10, the direct injection hydrogen injector 30a can be arranged at a position away from the combustion chamber 14 (inside the cylinder) of the hydrogen engine 10. Further, when the out-opening valve 60 provided on the downstream side of the in-cylinder jet pipe 50 is opened when the direct injection hydrogen injector 30a is opened, the out-opening valve 60 is opened due to the pressure rise in the in-cylinder jet pipe 50, and the jet of hydrogen gas is injected into the cylinder of the hydrogen engine 10. Further, when the direct injection hydrogen injector 30a is closed, since the out-opening valve 60 is closed, it is possible to suppress the intrusion of the combustion gas into the in-cylinder jet pipe 50 as the piston 13 of the hydrogen engine 10 rises.

[0048] Therefore, the heat load on the hydrogen injector 30a for direct injection by the combustion gas can be reduced. As a result, wear of the sliding portion of the hydrogen injector 30a for direct injection (specifically, the sliding portion between the valve body 35, the body 33, and the sleeve 45) can be suppressed. Along with this, wear of the metal touch portion (contact portion between the seat 39 and the valve body 35) of the nozzle portion 40 can be suppressed. Thus, the heat load on the hydrogen injector 30a for direct injection by the combustion gas can be reduced, and a decrease in the durability of the hydrogen injector 30a for direct injection can be suppressed. This is effective in suppressing a decrease in the durability of the hydrogen injector 30a for direct injection for which the cooling effect by hydrogen gas and the lubricating effect of the sliding portion cannot be expected.

[0049] In addition, the valve member 64, which is a movable part of the outward-opening valve 60, can be significantly reduced in weight compared to the valve body 35 of the hydrogen injector 30a for direct injection. As a result, the impact force of the valve member 64 at the time of valve closing against the valve seat member 62 is alleviated, so that wear of the metal touch portion (contact portion between the valve seat member 62 and the valve member 64) can be suppressed. Thereby, reliable sealing performance between the valve seat member 62 and the valve member 64 in the outward-opening valve 60 exposed to the combustion gas can be maintained over a long period. Consequently, intrusion of the combustion gas into the in-cylinder jet pipe 50 can be suppressed over a long period.

[0050] In addition, the seal ring 54 provided between the in-cylinder jet pipe 50 and the cylinder head 12 can suppress the intrusion of the combustion gas between the two. Thereby, sticking of the in-cylinder jet pipe 50 to the cylinder head 12 due to the unburned oil component in the combustion gas can be suppressed, and deterioration of the replacement workability of the direct injection unit 30 can be suppressed. Also, sagging of the seal member 46 can be suppressed, and the durability can be improved. Also, from the viewpoint of the durability and reliability of the outward-opening valve 60, it is effective to provide the seal ring 54 near the outward-opening valve 60, but the arrangement position of the seal ring 54 may be set in consideration of the heat resistance of the seal ring 54.

[0051] Further, by connecting the in-cylinder jet pipe 50 to the tip of the direct injection hydrogen injector 30a, the valve body 35 can be miniaturized and lightened in the axial direction compared to a conventional injector (see Patent Document 1). Along with this, the spring pressure of the spring 37 can be reduced. As a result, wear of the sliding part of the direct injection hydrogen injector 30a (specifically, the sliding part between the valve body 35, the body 33, and the sleeve 45) can be suppressed. Also, the impact force of the valve body 35 when closing the valve against the seat 39 can be mitigated, and wear of the metal touch part (the contact part between the seat 39 and the valve body 35) can be suppressed.

[0052] Further, by the cooperation of the in-cylinder jet pipe 50 and the seal ring 54, the heat load on the direct injection hydrogen injector 30a can be effectively reduced.

[0053] Also, due to the reduction of the heat load on the direct injection hydrogen injector 30a by mounting the direct injection hydrogen injector 30a upstream of the in-cylinder jet pipe 50, a rubber seal member 36 can be provided on the valve part 35b of the valve body 35, and sagging of the seal member 36 can be suppressed, improving durability. Also, by making the compression ratio of the seal member 36 constant due to the metal touch between the seat 39 and the valve body 35, sagging of the seal member 36 can be suppressed, improving durability. Therefore, reliable sealing performance by the seal member 36 between the valve body 35 and the seat 39 at the nozzle part 40 can be maintained over a long period.

[0054] Also, since it is a fuel injection device 28 of the in-cylinder injection type hydrogen engine 10, while suppressing the occurrence of abnormal combustion in the hydrogen engine 10, it is possible to realize a higher output of the hydrogen engine 10 by improving the filling efficiency of the intake air into the cylinder of the hydrogen engine 10.

[0055] Also, hydrogen gas is injected from the direct injection unit 30 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 direct injection unit 30 can supply hydrogen gas at an injection pressure at the same level as intake port injection.

[0056] Also, when injecting hydrogen gas by the direct injection hydrogen injector 30a, the high-speed jet of hydrogen gas is diffused conically 360° along the outer peripheral 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] Since this embodiment is a modification of Embodiment 1 (see FIGS. 1 to 7), the modified parts will be described, and the same reference numerals will be given to the same parts as in Embodiment 1, and duplicate descriptions will be omitted. FIG. 8 is a cross-sectional view showing the direct injection unit. As shown in FIG. 8, the direct injection unit 130 is obtained by adding a water injection injector 130a for injecting water into the in-cylinder jet pipe 50 to the direct injection unit 30 (see FIG. 2) of Embodiment 1.

[0058] On the upstream side of the tapered portion 52a of the in-cylinder jet pipe 50, a negative pressure chamber 152c with an enlarged diameter is formed. An ejector 155 is disposed in the negative pressure chamber 152c. The ejector 155 is formed in a tapered cylindrical shape with a gradually smaller diameter from the upstream side to the downstream side. The ejector 155 utilizes the flow of hydrogen gas to suck the water injected from the water injection injector 130a and mix the hydrogen gas and water.

[0059] On the side wall of the negative pressure chamber 152c, a water injection injector connection portion 156 communicating with the negative pressure chamber 152c is formed. The tip portion (water injection side end portion) of the water injection injector 130a is fitted to the water injection injector connection portion 156. The axis of the water injection injector connection portion 156 intersects (orthogonal in FIG. 8) 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 FIG. 2) of Embodiment 1. Therefore, in the water injection injector 130a, components and constituent parts common to the direct injection hydrogen injector 30a are assigned reference numerals in the 100s with the same last two digits, and the description thereof is omitted.

[0061] The water injection injector 130a has a nozzle portion 140 with a configuration different from that of the nozzle portion 40 (see FIG. 2) of Embodiment 1. The nozzle portion 140 is composed 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 disposed axially movably within the upstream end portion of the body 133. The hollow portion of the armature member 135a communicates with the hollow portion of the core 131.

[0062] The cylindrical member 135c is formed in a hollow cylindrical shape from a metal material. The upstream end portion 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 communicates with the hollow portion of the armature member 135a. A communication hole 135d penetrating in the radial direction is formed in the cylindrical member 135c.

[0063] The valve member 135b is formed in a spherical shape from a metal material. The valve member 135b is connected to the downstream end portion of the cylindrical member 135c by welding. The open end portion on the downstream side of the cylindrical member 135c is closed by the valve member 135b. The seat 139 is fitted within the downstream end portion of the body 133 and fixed by welding. The seat 139 is made of metal and formed in a bottomed cylindrical shape, and the seat portion 139a on the bottom side is disposed toward the downstream side. Injection holes 139b are formed in the seat portion 139a. Further, the core 131 and the body 133 may be formed of a magnetic material not related to hydrogen embrittlement.

[0064] In the water injection injector 130a, when the coil 132b of the electromagnetic solenoid 132 is de-energized, the valve member 135b of the valve body 135 abuts against, i.e., seats on, the seat portion 139a of the seat 139 due to the biasing force of the spring 137, resulting in a closed valve state. Therefore, water is not injected from the injection hole 139b of the seat 139.

[0065] Also, 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, i.e., unseat from, the seat portion 139a of the seat 139, resulting in an open valve state. Therefore, 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 injects water in a jet stream by operating in response to the input of an injection signal from the ECU 48 (see FIG. 1).

[0066] (Fuel supply system) FIG. 9 is a configuration diagram showing a fuel supply system. As shown in FIG. 9, the fuel supply system 170 is obtained by adding a water storage tank 176 to the fuel supply system 70 (see FIG. 7) in Embodiment 1. Water is stored in the water storage tank 176. A piping connection portion 130b (see FIG. 8) of the water injection injector 130a is connected to the water storage tank 176 via a water supply flow path 177.

[0067] A water supply pump 178, which is an electric pump, is provided in the middle of the water supply flow path 177. By driving the water supply pump 178, the water in the water storage tank 176 is pumped to the water injection injector 130a via the water supply flow path 177. Note that the water supply pump 178 is driven and controlled by the ECU 48 (see FIG. 1). The ECU 48 operates the water injection injector 130a to inject water during the period from the start to the end of the injection of hydrogen gas by the direct injection hydrogen injector 30a.

[0068] (Operation of the 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 the water injection injector 130a is activated during the period from the start to the end of the injection of the hydrogen gas from the direct injection hydrogen injector 30a. As a result, the hydrogen gas injected from the direct injection hydrogen injector 30a is injected toward the ejector 155. By utilizing the flow of the hydrogen gas, the water injected from the water injection injector 130a is inhaled, and the hydrogen gas and water are mixed. The mixture of the hydrogen gas and water, that is, the gas-liquid mixture, is injected into the combustion chamber 14 at a high speed jet through the outer opening valve 60 from the in-cylinder jet pipe 50. When the gas-liquid mixture is compressed in the combustion chamber 14, the water is completely vaporized, exerting the effect of lowering the mixture temperature, and when the combustion ends, it is discharged as vapor.

[0069] (Advantages of Embodiment 2) According to the present embodiment, the water injected from the water injection injector 130a is mixed with the hydrogen gas jet in the in-cylinder jet pipe 50. Since water is supplied in a liquid state, an inertial force can create flow turbulence in the in-cylinder jet pipe 50 to generate a gas-liquid mixture of hydrogen gas and water. This gas-liquid mixture is injected into the cylinder of the hydrogen engine 10 (see FIG. 1). Further, due to the latent heat of vaporization when water vaporizes, the compression end temperature is lowered, thereby improving the filling efficiency of the intake air introduced into the cylinder. As a result, the occurrence of knocking can be further suppressed, so the compression ratio can be increased. Also, since water is an inert gas, the combustion speed becomes slow, and the hydrogen gas can be burned at an appropriate combustion speed, reducing the amount of NOx generated.

[0070] Also, by means of the ejector 155, the water injected from the water injection injector 130a is inhaled using the flow of the hydrogen gas, and the hydrogen gas and water are mixed. As a result, the water injection pressure of the water injection injector 130a can be reduced, and the mixing property of the hydrogen gas and water can be improved. The ejector 155 can also be omitted.

[0071] [Embodiment 3] Since this embodiment is a modification of Embodiment 1 (see FIG. 1), the modified parts will be described, and the same reference numerals will be given to the same parts as in Embodiment 1, and redundant descriptions will be omitted. FIG. 10 is a cross-sectional view showing the periphery of the fuel injection device 28 of the hydrogen engine 10. As shown in FIG. 10, in this embodiment, a direct injection unit 30 is arranged instead of the spark plug 21 (see FIG. 1) in Embodiment 1. The in-cylinder jet pipe 50 of the direct injection unit 30 is inserted into an insertion hole 12d formed in the upper wall portion 12c of the combustion chamber 14 in the cylinder head 12 of the hydrogen engine 10. Thereby, at least a part of the direct injection hydrogen injector 30a is arranged outside the cylinder head 12. The insertion hole 12d penetrates the upper wall portion 12c. Further, the in-cylinder jet pipe 50 is 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 each of the intake side and the exhaust side. Also according to this embodiment, the same operations and effects as those of Embodiment 1 can be obtained.

[0072] [Embodiment 4] Since this embodiment is a modification of Embodiment 1 (see FIGS. 1 to 7), the modified parts will be described, and the same reference numerals will be given to the same parts as in Embodiment 1, and redundant descriptions will be omitted. FIG. 11 is a cross-sectional view showing the periphery of the fuel injection device 28 of the hydrogen engine 10. As shown in FIG. 11, this embodiment is obtained by adding a port injection unit 230 to the fuel injection device 28 (see FIG. 1) of Embodiment 1. That is, this embodiment is a multi-cylinder hydrogen engine 10 equipped with a dual injection system including a direct injection unit 30 for directly injecting hydrogen gas into the cylinder and a port injection unit 230 for injecting hydrogen gas into the intake port 16. The port injection unit 230 is integrally held in a housing (not shown) installed in 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 (see FIG. 2) of Embodiment 1. The in-cylinder jet pipe 50 has been partially modified. That is, as shown in FIG. 12, in this embodiment, the tapered portion 52a (see FIG. 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 that is 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 seal member 46.

[0074] (Port injection unit 230) FIG. 13 is a cross-sectional view showing the port injection unit 230. As shown in FIG. 13, the port injection unit 230 includes 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 FIG. 12) of this embodiment. For this reason, in the port injection hydrogen injector 230a, the same reference numerals are given to the components and constituent parts that are common to the direct injection hydrogen injector 30a, and the description thereof is omitted.

[0075] The port jet pipe 250 is formed in a circular tubular shape that extends linearly from a metal material that is resistant to hydrogen embrittlement. A stepped cylindrical injector connection portion 251 is concentrically formed at the base end portion (upstream end portion) of the port jet pipe 250. The tip portion (hydrogen gas injection side end portion) of the port injection hydrogen injector 230a is fitted into the injector connection portion 251. The seal member 46 elastically seals the space between the injector connection portion 251 and the body 33 of the port injection hydrogen injector 230a.

[0076] Inside the port jet pipe 250, a linear gas flow path 252 is formed to guide the jet of hydrogen gas injected from the port injection hydrogen injector 230a into the intake port 16 (see FIG. 11) of the hydrogen engine 10. At the upstream end of the gas flow path 252, a gas flow path 252, a tapered portion 252d, and a straight portion 252e are formed in the same manner as the gas flow path 52, the tapered portion 52d, and the straight portion 52e of the in-cylinder jet pipe 50 (see FIG. 12). The remaining pipe-shaped portion of the port jet pipe 250 excluding the injector connection portion 251 has an outer diameter smaller than the outer diameter of the remaining pipe-shaped portion of the in-cylinder jet pipe 50 excluding the injector connection portion 51. An elastic cylindrical seal member 256 is attached to the outer peripheral surface of the downstream end of the injector connection portion 251. The seal member 256 is made of rubber.

[0077] (Installation of the port injection unit 230 for the hydrogen engine 10) As shown in FIG. 11, the port jet pipe 250 of the port injection unit 230 is inserted into an insertion hole 12f formed in the upper wall portion 12e of the intake port 16 in the cylinder head 12 of the hydrogen engine 10. Thereby, at least a part of the port injection hydrogen injector 230a is disposed outside the cylinder head 12. The lower end opening of the insertion hole 12f is located on the downstream side of the intake port 16 with respect to the 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 disposed at a position close to the umbrella portion 17a of the intake valve 17 in a closed valve state, which is the downstream portion of the intake port 16. Also, the seal member 256 seals the space between the cylinder head 12 and the port jet pipe 250. A branch flow path 72a branched from the hydrogen gas supply flow path 72 (see FIG. 7) is connected to the pipe connection portion 30b of the port injection hydrogen injector 230a.

[0079] The ECU 48 is set to perform injection control of the direct injection hydrogen injector 30a and the port injection hydrogen injector 230a based on an injection map. As shown in FIG. 14, the injection map is set such that the characteristic line L1 can be obtained by operating the port injection hydrogen injector 230a in the light load region. Also, in the medium load and high load regions, the injection map is set such that the characteristic line L2 can be obtained by operating both the port injection hydrogen injector 230a and the direct injection hydrogen injector 30a.

[0080] (Advantages of Embodiment 4) According to the present embodiment, 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 condition of the hydrogen engine 10, efficient operation can be performed.

[0081] That is, in the light load region, by selecting the port injection hydrogen injector 230a and injecting and supplying the hydrogen gas jet into the intake port 16, the inhomogenization of the air-fuel mixture in the light load region can be improved. Specifically, the penetration force of the hydrogen jet directly injected into the cylinder through the in-cylinder jet pipe 50 by the direct injection hydrogen injector 30a has a faster decay after injection compared to the spray penetration force of a direct injection gasoline engine, and there may be problems remaining in the homogenization of the air-fuel mixture. In particular, in the light load region, since the flow velocity during intake is slow and the turbulence intensity is small, combustion deterioration due to an inhomogeneous air-fuel mixture becomes a problem. To address this problem, in the light load region, by injecting and supplying the hydrogen gas injected from the port injection hydrogen injector 230a into the intake port 16 through the port jet pipe 250, the inhomogenization of the air-fuel mixture in the light load region can be improved.

[0082] In the medium load and high load regions, while the hydrogen gas injected from the port injection hydrogen injector 230a is injected and supplied to the intake port 16 through the port jet pipe 250, the hydrogen gas injected from the direct injection hydrogen injector 30a is injected and supplied into the cylinder through the in-cylinder jet pipe 50. Thereby, an improvement in the filling efficiency, which is an advantage of the direct injection hydrogen engine, can be expected. 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] Further, by providing the port jet pipe 250 that guides the jet of the hydrogen gas injected from the port injection hydrogen injector 230a to the intake port 16 of the hydrogen engine 10, the jet of the hydrogen gas can be injected near the combustion chamber 14. Thereby, while suppressing the occurrence of abnormal combustion in the hydrogen engine 10, it is possible to achieve a higher output of the hydrogen engine 10.

[0084] [Embodiment 5] Since this embodiment is a modification of Embodiment 4 (see FIG. 11), the modified part will be described, and the same reference numerals will be given to the same parts as in Embodiment 4, and duplicate descriptions will be omitted. FIG. 15 is a cross-sectional view showing the peripheral part of the fuel injection device 28 of the hydrogen engine 10. As shown in FIG. 15, in this embodiment, similar to Embodiment 3 (see FIG. 10), a direct injection unit 30 is arranged instead of the spark plug 21 (see FIG. 11) in Embodiment 4. Also in this embodiment, the same operations and effects as in Embodiment 4 can be obtained.

[0085] [Other Embodiments] The present invention is not limited to the above-described embodiments, and modifications can be made without departing from the scope of the present invention. For example, the present invention is not limited to vehicles such as automobiles, and may be applied as a fuel injection device for aircraft, ships, and other hydrogen engines. Further, the outward-opening valve 60 is not limited to the downstream end of the in-cylinder jet pipe 50, and may be provided upstream of the downstream end thereof.

Description of Reference Numerals

[0086] 10 Hydrogen engine 12 Cylinder head 14 Combustion chamber (inside the cylinder) 16 Intake port 28 Fuel injection device 30 Direct injection unit 30a Direct injection hydrogen injector 50 In-cylinder jet pipe 60 Exhaust valve 130 Direct injection unit 130a Water injection injector 230 Port injection unit 230a Port injection hydrogen injector 250 Port jet pipe

Claims

1. A fuel injection device including a direct injection hydrogen injector that injects hydrogen gas, At least a portion of the direct injection hydrogen injector is disposed outside a cylinder head of a hydrogen engine, an in-cylinder jet pipe for guiding the jet of hydrogen gas injected from the direct injection hydrogen injector into a cylinder of the hydrogen engine; An external opening valve is provided on the downstream side of the in-cylinder jet pipe, The outer opening valve is normally closed, and is opened by a pressure increase in the in-cylinder jet pipe when the direct injection hydrogen injector is opened.

2. 2. The fuel injection system of claim 1, a water injector that injects water into the in-cylinder jet pipe;

3. 3. A fuel injection device according to claim 1 or 2, The hydrogen injector includes a port injection hydrogen injector that injects the hydrogen gas. At least a portion of the port injection hydrogen injector is disposed outside the cylinder head, a port jet pipe that guides the jet of hydrogen gas injected from the port injection hydrogen injector to an intake port of the hydrogen engine.

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