Fuel injection device

Abstract

The present application relates to a fuel injection device. The fuel injection device is provided with a fuel injection valve at a position corresponding to an intake port in an internal combustion engine. The fuel injection valve is provided with a main body and a valve needle provided inside the main body. The fuel injection valve is located closer to a piston of the internal combustion engine than the intake port. Between a valve seat of the fuel injection valve and a combustion chamber of the internal combustion engine, there is a separate fuel injection passage for flowing gaseous fuel. With respect to a flow passage cross section of the gaseous fuel in the fuel injection passage, on a certain length in an extension direction of the fuel injection passage, the flow passage cross section of the gaseous fuel on a side closer to the piston of the internal combustion engine is larger than on a side closer to a spark plug of the internal combustion engine.

Description

Technical Field

[0001] This disclosure relates to a fuel injection device. Background Technology

[0002] As a fuel injection device for an internal combustion engine, a fuel injection device with a fuel injection valve for injecting fuel into the combustion chamber of the internal combustion engine is known. The fuel injection valve has a main body and a valve needle disposed inside the main body. The valve is closed by pressing the valve needle against a valve seat. Conversely, when the valve needle is moved away from the valve seat, the fuel injection valve opens. Thus, fuel is injected from the fuel injection valve into the combustion chamber.

[0003] In the fuel injection valve disclosed in Japanese Patent Application Publication No. 2017-125475, a valve seat is formed at the opening of the nozzle formed in the main body. A valve core, formed at the tip of a valve needle, is pressed against this valve seat. When the valve needle is moved in a direction protruding from the fuel injection valve, the valve core moves away from the valve seat. This opens the fuel injection valve. At this time, fuel is injected between the valve seat and the valve core.

[0004] Furthermore, in the aforementioned fuel injection valve, the opening of the injection orifice is elliptical. Therefore, when the movement (lift) of the valve needle from the position where the valve core presses against the valve seat is small, fuel is easily injected along the long axis of the injection orifice opening and is difficult to inject along the short axis. By adjusting the fuel injection direction in such a fuel injection valve, it is possible to prevent fuel from hitting components such as the intake and exhaust valves of the internal combustion engine.

[0005] However, the adjustment of the fuel injection direction from the fuel injection valve described in Japanese Patent Application Publication No. 2017-125475 is effective when the valve needle lifts slightly, but becomes difficult to perform effectively when the valve needle lifts significantly. This is because when the valve needle lifts significantly, the fuel flow rate between the valve seat and the valve core increases, thus reducing the influence of the orifice opening shape on the fuel injection direction.

[0006] Therefore, when injecting low-density gaseous fuel from the fuel injection valve, the valve needle lift must be increased to ensure the necessary fuel injection quantity, making it difficult to effectively adjust the injection direction of the gaseous fuel from the fuel injection valve. As a result, the gaseous fuel injected from the fuel injection valve may easily come into contact with components such as the intake and exhaust valves in the internal combustion engine. Summary of the Invention

[0007] In one aspect of this disclosure, a fuel injection device is provided. The fuel injection device includes a fuel injection valve located in an internal combustion engine at a position corresponding to the intake port. The fuel injection valve includes a body and a valve needle disposed inside the body. The fuel injection valve is configured to close by pressing the valve needle against a valve seat, and to open by moving the valve needle away from the valve seat, thereby injecting gaseous fuel into the combustion chamber of the internal combustion engine. The fuel injection valve is positioned closer to the piston of the internal combustion engine than the intake port. Between the valve seat and the combustion chamber, there is a separate fuel injection passage for the flow of the gaseous fuel. For the flow cross-section of the gaseous fuel in the fuel injection passage, over a defined length in the extending direction of the fuel injection passage, the flow cross-section of the gaseous fuel on the side closer to the piston of the internal combustion engine is larger than that on the side closer to the spark plug of the internal combustion engine. Attached Figure Description

[0008] Figure 1 This is a schematic diagram showing the structure of the combustion chamber and its surroundings in the internal combustion engine of the first embodiment.

[0009] Figure 2 It means from Figure 1 Below is a schematic diagram showing the state of the combustion chamber and its surroundings.

[0010] Figure 3 It means from Figure 1 The diagram shows a general view of the combustion chamber and its surroundings, viewed from the direction of arrow A.

[0011] Figure 4 It means Figure 1 A cross-sectional view of the internal structure of the fuel injection valve of an internal combustion engine.

[0012] Figure 5 It means Figure 1 A cross-sectional view of the internal structure of the fuel injection valve of an internal combustion engine.

[0013] Figure 6 It means Figure 4 and Figure 5 A cross-sectional view of the flow section of gaseous fuel in the nozzle of the fuel injection valve shown.

[0014] Figure 7 This is a cross-sectional view showing the fuel injection valve and its surrounding area in the internal combustion engine of the second embodiment, enlarged.

[0015] Figure 8 It means Figure 7 The diagram shows a cross-sectional view of the flow section of gaseous fuel through the nozzle of the fuel injection valve in an internal combustion engine.

[0016] Figure 9 This is a cross-sectional view showing another example of the flow section of gaseous fuel in the fuel injection path.

[0017] Figure 10 This is a cross-sectional view showing another example of the flow section of gaseous fuel in the fuel injection path.

[0018] Figure 11 This is a cross-sectional view showing another example of the flow section of gaseous fuel in the fuel injection path. Detailed Implementation

[0019] [First Implementation Method]

[0020] The following is for reference Figures 1 to 8 The first embodiment of the fuel injection device will be described.

[0021] like Figure 1 As shown, the internal combustion engine includes a cylinder block 11, a cylinder head 12, and a piston 13. An intake port 14 and an exhaust port 15 are formed in the cylinder head 12. The intake port 14 and exhaust port 15 are connected to a combustion chamber 16 defined by the cylinder block 11, cylinder head 12, and piston 13. The piston 13 reciprocates within the cylinder block 11 as driven by the internal combustion engine. With this reciprocating motion of the piston 13, the intake stroke, compression stroke, expansion stroke, and exhaust stroke of the internal combustion engine are repeatedly performed.

[0022] The cylinder head 12 is equipped with an intake valve 17, an exhaust valve 18, a spark plug 19, and a fuel injection valve 20. The intake valve 17 opens and closes in conjunction with the operation of the internal combustion engine, thereby connecting or disconnecting the intake port 14 from the combustion chamber 16. The intake valve 17 is open during the intake stroke and closed during the stroke outside the intake stroke. The exhaust valve 18 opens and closes in conjunction with the operation of the internal combustion engine, thereby connecting or disconnecting the exhaust port 15 from the combustion chamber 16. The exhaust valve 18 is open during the exhaust stroke and closed during the stroke outside the exhaust stroke.

[0023] During the intake stroke, when intake valve 17 opens, air is drawn into combustion chamber 16 through intake port 14. Gaseous fuel is injected into combustion chamber 16 through fuel injection valve 20. Then, during the compression stroke, the air and gaseous fuel in combustion chamber 16 are compressed. By igniting this compressed gaseous fuel with spark plug 19, combustion occurs, and the stroke transitions to expansion. Afterward, during the exhaust stroke, exhaust valve 18 opens, and the combusted exhaust gas is discharged from combustion chamber 16 to exhaust port 15.

[0024] <Detailed Structure of Combustion Chamber 16 and its Surroundings in an Internal Combustion Engine>

[0025] Figure 2 and Figure 3 Showing from Figure 1 Below and Figure 1 Observe the combustion chamber 16 and its surroundings in the direction of arrow A. Figure 2 and Figure 3 It can be seen that there are two intake ports 14 and two intake valves 17 respectively for each combustion chamber 16, and they are located in the combustion chamber 16. Figure 1 and Figure 2 The left half is arranged side by side. Two exhaust ports 15 and two exhaust valves 18 are each provided relative to one combustion chamber 16, and are positioned within the combustion chamber 16. Figure 1 and Figure 2 The right half is configured in a side-by-side manner.

[0026] like Figure 2 As shown, the spark plug 19 is positioned in the center of the combustion chamber 16, between the intake valve 17 and the exhaust valve 18. Figures 1-3 As shown, the fuel injection valve 20 is inserted relative to the cylinder head 12 toward the combustion chamber 16, and is positioned at a position corresponding to the intake port 14 and closer to the piston 13 than the intake port 14, which forms part of the intake passage formed in the cylinder head 12. The fuel injection device of the internal combustion engine includes the aforementioned fuel injection valve 20.

[0027] <Construction of fuel injection valve 20>

[0028] like Figure 4 and Figure 5 As shown, the valve needle 22 and valve seat 23 are located inside the body 21 of the fuel injection valve 20. The aforementioned gaseous fuel is supplied to the interior of the body 21. A combustion chamber 16 is formed in the body 21, extending from the valve seat 23 towards the internal combustion engine. Figure 1 A separate nozzle 24 extends from the combustion chamber 16. The nozzle 24 is connected to the combustion chamber 16. A separate fuel injection passage 25 is formed through the inner wall of the nozzle 24. The fuel injection passage 25 is used to allow the gaseous fuel to flow and is located between the valve seat 23 of the fuel injection valve 20 and the combustion chamber 16.

[0029] The valve needle 22 can move along its length inside the body 21 by the elastic force of the spring and the electromagnetic force of the solenoid. The valve needle 22 moves closer to or further away from the valve seat 23. A valve core 26 is formed at the end of the valve needle 22 near the valve seat 23.

[0030] The fuel injection valve 20 moves the valve needle 22 close to the valve seat 23, such as Figure 4 As shown, the valve core 26 is pressed against the valve seat 23, thereby closing the valve. Additionally, the fuel injection valve 20 is controlled by... Figure 5As shown, the valve needle 22 is moved away from the valve seat 23 towards the valve core 26 to open the valve, and the gaseous fuel is injected into the combustion chamber 16 along with the opening of the valve. At this time, the gaseous fuel is injected into the combustion chamber 16 from the inside of the nozzle 24 in the fuel injection valve 20, that is, the fuel injection passage 25.

[0031] <Shape of the flow cross section of gaseous fuel in fuel injection passage 25>

[0032] Figure 6 This indicates the cross-sectional area of ​​the gaseous fuel flow in the fuel injection passage 25. From Figure 6 It can be seen that the flow cross-section of the fuel injection passage 25 on the side closer to the piston 13 of the internal combustion engine is larger than that on the side closer to the spark plug 19 of the internal combustion engine. In other words, Figure 1 The aforementioned flow section ratio on the lower side Figure 1 The upper side is larger.

[0033] The flow section of the fuel injection passage 25, on the side near the spark plug 19, protrudes from the flow section near the piston 13 toward the spark plug 19. Furthermore, the flow section of the fuel injection passage 25 on the side near the spark plug 19 is aligned with the intake port 14 in that direction. Figure 6 It forms a symmetrical shape centered on the center of the fuel injection passage 25 in the left and right directions.

[0034] The aforementioned flow section of the fuel injection passage 25 takes the aforementioned shape over a defined length in the extending direction of the fuel injection passage 25.

[0035] Next, the effects of the fuel injection device in this embodiment will be explained.

[0036] (1-1) When gaseous fuel is injected into the combustion chamber 16 from the fuel injection valve 20, in order to reduce NOx generated after the combustion of the gaseous fuel, it is preferable to mix the gaseous fuel with the air in the combustion chamber 16 in a homogeneous manner. However, when, for example, gaseous fuel is injected diffusely from the fuel injection valve 20 to make the gaseous fuel and air homogeneous in the combustion chamber 16, the injected gaseous fuel may come into contact with components such as the intake valve 17 and the exhaust valve 18.

[0037] In the aforementioned fuel injection device, gaseous fuel injected from the fuel injection valve 20 passes through the fuel injection passage 25 located between the valve seat 23 of the fuel injection valve 20 and the combustion chamber 16, and is then injected into the combustion chamber 16. Therefore, the diffusion pattern of the gaseous fuel injected into the combustion chamber 16 is influenced by the shape of the flow cross-section of the gaseous fuel in the fuel injection passage 25. The flow cross-section closer to the piston 13 of the internal combustion engine is larger than that closer to the spark plug 19. This suppresses the diffusion of gaseous fuel injected from the fuel injection valve 20 into the combustion chamber 16 towards the spark plug 19 within the combustion chamber 16. Consequently, it is possible to prevent gaseous fuel from encountering components such as the intake valve 17 and exhaust valve 18 within the combustion chamber 16.

[0038] When gaseous fuel injected from fuel injection valve 20 into combustion chamber 16 encounters intake valve 17 at the end of its opening phase, the gaseous fuel may enter intake port 14 after encountering intake valve 17. In this case, when intake valve 17 opens again, the gaseous fuel may mix with air drawn into combustion chamber 16 from intake port 14 and also be drawn into combustion chamber 16. This gaseous fuel may then come into contact with high-temperature parts such as exhaust valve 18, causing abnormal combustion. Furthermore, if gaseous fuel injected from fuel injection valve 20 directly encounters exhaust valve 18, the gaseous fuel may ignite due to the high temperature of exhaust valve 18, causing abnormal combustion. However, such abnormal combustion can be avoided by preventing gaseous fuel injected from fuel injection valve 20 from encountering intake valve 17 and exhaust valve 18 as described above.

[0039] (1-2) The flow section of the fuel injection passage 25, on the side near the spark plug 19, protrudes from the flow section near the piston 13 toward the spark plug 19. Furthermore, the flow section on the side near the spark plug 19 is symmetrical about the center of the fuel injection passage 25 in the arrangement direction of the intake ports 14. Thus, the gaseous fuel injected from the fuel injection valve 20 into the combustion chamber 16... Figure 3 The diffusion is as shown by the dashed line. As a result, it is possible to suppress the diffusion of the gaseous fuel towards the intake valve 17 within the combustion chamber 16.

[0040] (1-3) The structure that prevents gaseous fuel from encountering components such as the intake valve 17 and exhaust valve 18 within the combustion chamber 16 is achieved through the nozzle 24 in the body 21 of the fuel injection valve 20. Specifically, the aforementioned fuel injection passage 25 is formed on the inner wall of the nozzle 24. Therefore, by using only the fuel injection valve 20 with the aforementioned fuel injection passage 25, it is possible to prevent gaseous fuel from encountering components such as the intake valve 17 and exhaust valve 18 within the combustion chamber 16, without needing to modify any part of the internal combustion engine other than the fuel injection valve 20.

[0041] [Second Implementation]

[0042] Next, refer to Figure 7 and Figure 8 A second embodiment of the fuel injection device will be described.

[0043] In this embodiment, instead of forming the fuel injection passage 25 in the fuel injection valve 20 as in the first embodiment, ... Figure 7 As shown, a fuel injection passage 25 is formed in the cylinder head 12 of the internal combustion engine. Specifically, an insertion portion 31 for inserting a fuel injection valve 20 is formed in the cylinder head 12. A through hole 33 is formed in the partition wall 32 of the cylinder head 12 separating the insertion portion 31 and the combustion chamber 16. The through hole 33 connects the injection orifice 24 of the fuel injection valve 20 to the combustion chamber 16. In this embodiment, the fuel injection passage 25 is formed by the inner wall of the through hole 33. Figure 8 As shown, in this embodiment, the flow cross section of the gaseous fuel in the nozzle 24 of the fuel injection valve 20 is set to be circular.

[0044] According to this embodiment, in addition to the effects of (1-1) and (1-2) of the first embodiment, the following effects can also be obtained.

[0045] (2-1) The structure that prevents gaseous fuel from encountering components such as the intake valve 17 and exhaust valve 18 in the combustion chamber 16 is achieved through a through hole 33 in the partition wall 32 located between the injection hole 24 of the fuel injection valve 20 and the combustion chamber 16 in the cylinder head 12. Specifically, a fuel injection passage 25 is formed using the inner wall of the through hole 33. Therefore, by simply forming the fuel injection passage 25 in the partition wall 32 of the cylinder head 12 using the inner wall of the through hole 33, it is possible to prevent gaseous fuel from encountering components such as the intake valve 17 and exhaust valve 18 in the combustion chamber 16. In this case, it is not necessary for the fuel injection valve 20 to have a special structure in order to prevent gaseous fuel from encountering components such as the intake valve 17 and exhaust valve 18 in the combustion chamber 16. Therefore, the fuel injection valve 20 can be designed to accommodate increases in fuel injection quantity, thus increasing the design freedom of the fuel injection valve 20.

[0046] [Other Implementation Methods]

[0047] It should be noted that the above embodiments can also be modified in the following ways. The above embodiments and the following modifications can be combined with each other to implement them within the scope of technical non-inconsistency.

[0048] In both the first and second embodiments, the flow cross-section of the gaseous fuel in the fuel injection passage 25 can be appropriately modified. For example, consider changing the flow cross-section to... Figures 9-11That shape.

Claims

1. A fuel injection device, wherein the fuel injection device is provided with a fuel injection valve located in a position corresponding to an intake port in an internal combustion engine, the fuel injection valve is provided with a main body and a valve needle provided inside the main body, the fuel injection valve is configured to close by pressing the valve needle against a valve seat, and on the other hand, to open by moving the valve needle in a direction away from the valve seat, with the opening, gas fuel is injected into a combustion chamber of the internal combustion engine, the fuel injection valve is disposed closer to a piston of the internal combustion engine than to the intake port, between the valve seat and the combustion chamber, there is a separate fuel injection passage for flowing the gas fuel, for the flow cross section of the gas fuel in the fuel injection passage, on a certain length in the extension direction of the fuel injection passage, the flow cross section of the gas fuel on the side closer to the piston of the internal combustion engine is larger than on the side closer to a spark plug of the internal combustion engine, the spark plug is provided to a cylinder head.

2. The fuel injection device according to claim 1, the flow cross section on the side closer to the spark plug in the flow cross section of the fuel injection passage is protruded in a direction toward the spark plug from the flow cross section on the side closer to the piston, and becomes a symmetrical shape with the center of the fuel injection passage as the center in the arrangement direction of the intake port.

3. The fuel injection device according to claim 1 or 2, in the main body, a separate injection hole for injecting the gas fuel is formed in a manner extending from the valve seat toward the combustion chamber, the fuel injection passage is formed by the inner wall of the injection hole.

4. The fuel injection device according to claim 1 or 2, a member between the fuel injection valve and the combustion chamber in the internal combustion engine is formed with a separate through hole through which the gas fuel injected from the fuel injection valve passes, the fuel injection passage is formed by the inner wall of the through hole.

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