Fuel injection device and engine

Abstract

This fuel injection device for injecting fuel into a combustion chamber of an engine comprises a nozzle body in which, in a distal end portion thereof, a plurality of injection holes communicating with the combustion chamber and configured to inject the fuel are formed. The plurality of injection holes includes: at least one diffusion injection hole that connects to a diffusion injection port opened in the combustion chamber and has a diffusion outlet portion configured such that a length in a first direction of a cross section increases toward the diffusion injection port; and at least one penetrating injection hole that connects to a penetrating injection port opened in the combustion chamber and has a penetrating outlet portion configured such that a cross-sectional area does not increase toward the penetrating injection port.

Description

Fuel injection system and engine

[0001] The present disclosure relates to a fuel injection device that injects fuel into a combustion chamber of an engine, and an engine equipped with the fuel injection device. This application claims priority to Japanese Patent Application No. 2024-097139, filed with the Japan Patent Office on June 17, 2024, the contents of which are incorporated herein by reference.

[0002] Conventionally, fuel injection devices have applied various technologies to promote the mixing of fuel and air injected into a combustion chamber. For example, Patent Document 1 describes an arrangement of nozzle holes that can reduce the influence of the Coanda effect on fuel spray. Patent Document 2 describes the configuration of a valve body including a valve seat and nozzle holes, and the configuration of a needle valve, which enable high atomization of fuel spray.

[0003] JP 2018-150953 A JP 2012-246897 A

[0004] Incidentally, when an engine is operating, a swirling flow such as a swirl flow or a tumble flow occurs within the combustion chamber. Therefore, the combustion chamber may include a region with a large amount of air and a region with a small amount of air. By supplying a large amount of fuel to the region with a large amount of air and a small amount of fuel to the region with a small amount of air, it is possible to further promote the mixing of the fuel injected into the combustion chamber with the air (further improving the air utilization rate within the combustion chamber). However, the technologies disclosed in Patent Documents 1 and 2 do not take into account the swirling flow within the combustion chamber when injecting fuel into the combustion chamber.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a fuel injection device that can further promote mixing of fuel and air injected into a combustion chamber.

[0006] In order to achieve the above-mentioned object, the fuel injection device of the present disclosure is a fuel injection device that injects fuel into a combustion chamber of an engine, and includes a nozzle body having a plurality of nozzle holes formed at its tip that communicate with the combustion chamber and are configured to inject the fuel, and the plurality of nozzle holes include at least one diffusion nozzle hole that is connected to a diffusion nozzle hole that opens into the combustion chamber and has a diffusion outlet portion that is configured so that the length of the cross section in a first direction expands toward the diffusion nozzle hole, and at least one through nozzle hole that is connected to a through nozzle hole that opens into the combustion chamber and has a through outlet portion that is configured so that the cross-sectional area does not expand toward the through nozzle hole.

[0007] According to the fuel injection device of the present disclosure, the mixing of the fuel and air injected into the combustion chamber can be further promoted.

[0008] FIG. 1 is a cross-sectional view schematically showing the configuration of a fuel injection device according to one embodiment. FIG. 2 is a view for explaining the configuration of a diffusion outlet portion of a diffusion injection hole according to one embodiment. FIG. 3 is a view for explaining the configuration of a through-through outlet portion of a through-through injection hole according to one embodiment. FIG. 4 is a front view of a nozzle body according to some embodiments, viewed from a combustion chamber. FIG. 5 is a view for explaining the configuration of a through-through outlet portion of a through-through injection hole according to some embodiments. FIG. 6 is a longitudinal cross-sectional view schematically showing the configuration of an opposed-piston engine including a fuel injection device according to some embodiments. FIG. 7 is a cross-sectional view schematically showing the configuration of a first fuel injection device shown in FIG. 6. FIG. 8 is a cross-sectional view schematically showing the configuration of the first fuel injection device shown in FIG. 6. FIG. 9 is a front view of a nozzle body according to the first fuel injection device shown in FIG. 6, viewed from a cylinder bore. FIG. 10 is a view showing an example of the injection direction of fuel injected from the first diffusion injection hole, the second diffusion injection hole, the first through-through injection hole, and the second through-through injection hole.

[0009] A fuel injection device and an engine according to an embodiment of the present disclosure will be described below with reference to the drawings. The embodiment shows one aspect of the present disclosure, but does not limit the present disclosure and can be modified as desired within the scope of the technical concept of the present disclosure.

[0010] <Fuel Injection Device> A fuel injection device according to the present disclosure injects fuel into a combustion chamber of an engine. The engine is not particularly limited and may be, for example, a diesel engine. In some embodiments, the engine is a V-type engine or a four-stroke engine. In some embodiments, the engine is an opposed-piston engine in which two pistons are arranged opposite each other in one cylinder. The opposed-piston engine may also be a horizontally opposed engine in which two pistons are arranged opposite each other in the horizontal direction. In some embodiments, the fuel injection device is so-called center-mounted, and is arranged at a position corresponding to the center of the combustion chamber and injects fuel into the combustion chamber from the upper center. In some embodiments, the fuel injection device is so-called side-mounted, and is arranged at a position corresponding to the outer periphery of the combustion chamber and injects fuel into the combustion chamber from the side.

[0011] (Configuration) Figure 1 is a cross-sectional view that shows a schematic configuration of a fuel injection device 1 according to one embodiment. As shown in Figure 1, the fuel injection device 1 includes a nozzle body 2 having a plurality of injection holes 3, 4 formed in a tip portion 6. Each of the plurality of injection holes 3, 4 communicates with a combustion chamber 101 and is configured to inject fuel F. The plurality of injection holes 3, 4 includes a diffusion injection hole 3 and a through injection hole 4.

[0012] In one embodiment, as illustrated in Fig. 1 , the nozzle body 2 has a fuel flow path 7 formed therein that extends along the axis O. The tip portion 6 of the nozzle body 2 has an outer shape that approaches the axis O as it approaches the combustion chamber 101. The outer shape of this tip portion 6 is convexly curved so as to smoothly change, and is generally hemispherical. The diffusion injection hole 3 and the through injection hole 4 each communicate with the fuel flow path 7. Hereinafter, the direction in which the axis O of the nozzle body 2 extends will be referred to as the extension direction Dx. Within the extension direction Dx, the direction toward the combustion chamber 101 will be referred to as the tip side of the extension direction Dx, and the direction toward the opposite side of the combustion chamber 101 will be referred to as the base side of the extension direction Dx.

[0013] The diffusion nozzle hole 3 has a diffusion outlet portion 10 that is continuous with the diffusion nozzle hole 8 that opens into the combustion chamber 101. In the embodiment illustrated in Fig. 1, the diffusion nozzle hole 3 is located closer to the fuel flow path 7 than the diffusion outlet portion 10, and includes an upstream portion 12 that is connected at one end to the fuel flow path 7 and at the other end to the diffusion outlet portion 10. The upstream portion 12 has a constant cross-sectional area over the entire direction in which the diffusion axis O1 of the diffusion nozzle hole 3 extends, and has a circular cross-sectional shape.

[0014] The injection direction Da of the diffusion nozzle hole 3 is perpendicular to the cross section of the diffusion nozzle hole 8 and is the direction of extension of a virtual line (not shown) passing through the center of this cross section. In one embodiment, the diffusion nozzle hole 3 is formed in the tip portion 6 of the nozzle body 2 so that the injection direction Da is inclined with respect to the extension direction Dx. Specifically, the diffusion nozzle hole 3 is formed in the tip portion 6 of the nozzle body 2 so that the diffusion axis O1 extends linearly and is inclined with respect to the axis O. In the present disclosure, such a diffusion nozzle hole 3 is referred to as a first diffusion nozzle hole 3A(3). In some embodiments, the diffusion nozzle hole 3 is formed in the tip portion 6 of the nozzle body 2 so that the injection direction Da extends along the extension direction Dx. Note that the present disclosure is not limited to the diffusion axis O1 extending linearly. The diffusion axis O1 may be bent or curved. The present disclosure is not limited to the number of diffusion nozzle holes 3 being one. In some embodiments, the fuel injection device 1 includes multiple diffusion nozzle holes 3.

[0015] 2 is a diagram illustrating the configuration of the diffusion outlet section 10 of the diffusion nozzle 3 according to one embodiment. As shown in FIG. 2, the diffusion outlet section 10 is configured such that the length of the cross section in a first direction D1 increases toward the diffusion nozzle 8. In one embodiment, the length of the diffusion outlet section 10 in a second direction D2 perpendicular to the first direction D1 of the cross section decreases toward the diffusion nozzle 8. In one embodiment, the diffusion outlet section 10 is configured such that the cross-sectional area is constant from an inlet 11 on the opposite side of the diffusion nozzle 8 toward the diffusion nozzle 8. The inlet 11 opens into the fuel flow path 7.

[0016] Specifically, the cross section of the inlet 11 of the diffusion outlet section 10 is referred to as the first cross section A1, the cross section of the diffusion nozzle 8 is referred to as the second cross section A2, and the cross section between the first cross section A1 and the second cross section A2 is referred to as the third cross section A3. The second cross section A2 and the third cross section A3 each have an elliptical shape, while the first cross section A1 has a circular shape. The lengths in the first direction D1 are greatest for the second cross section A2, the third cross section A3, and the first cross section A1, in that order. The lengths in the second direction D2 are greatest for the first cross section A1, the third cross section A3, and the second cross section A2, in that order. The first cross section A1, the second cross section A2, and the third cross section each have the same cross-sectional area. In the embodiment illustrated in FIG. 2 , the major axis L1 of the second cross section A2 (the elliptical shape of the diffusion nozzle 8) extends along the first direction D1, and the minor axis L2 of the second cross section A2 extends along the second direction D2. The diffusion nozzle hole 3 having such a diffusion outlet portion 10 diffuses the fuel F along the first direction D1 and injects it into the combustion chamber 101.

[0017] As shown in Figure 1, the through-hole injection hole 4 has a penetration outlet portion 16 that continues to a penetration nozzle 14 that opens into the combustion chamber 101. This penetration outlet portion 16 is configured so that its cross-sectional area does not increase toward the penetration nozzle 14. In the example shown in Figure 1, one end of the penetration outlet portion 16 is connected to the fuel flow path 7, and the other end is connected to the penetration nozzle 14. The penetration outlet portion 16 has a constant cross-sectional area over the entire direction in which the penetration axis O2 of the through-hole injection hole 4 extends, and has a circular cross-sectional shape.

[0018] The injection direction Db of the through-hole 4 is perpendicular to the cross section of the through-hole 14 and is the direction of an imaginary line (not shown) passing through the center of this cross section. In one embodiment, the through-hole 4 is formed in the tip 6 of the nozzle body 2 so that the injection direction Db extends along the extension direction Dx. Specifically, the through-hole 4 is formed in the tip 6 of the nozzle body 2 so that the penetration axis O2 extends linearly along the axis O. Furthermore, this penetration axis O2 passes through the same path as the axis O (in FIG. 2, the penetration axis O2 is deviated from the axis O for the sake of explanation). In the present disclosure, such a through-hole 4 is referred to as a first through-hole 4A(4). In some embodiments, the through-hole 4 is formed in the tip 6 of the nozzle body 2 so that the injection direction Db is inclined with respect to the extension direction Dx. Note that the present disclosure is not limited to the penetration axis O2 extending linearly. The through-hole axis O2 may be bent or curved along the way. The present disclosure does not limit the number of through-holes 4 to one. In some embodiments, the fuel injection device 1 includes multiple through-holes 4.

[0019] 3 is a diagram illustrating the configuration of the penetration outlet 16 of the penetration nozzle 4 according to one embodiment. The penetration outlet 16 is configured so that the cross-sectional area is constant and the cross-sectional shape is the same from the penetration inlet 15 on the opposite side of the penetration nozzle 14 to the penetration nozzle 14. The penetration inlet 15 opens into the fuel flow path 7.

[0020] Specifically, the cross section of the penetration inlet 15 of the penetration outlet portion 16 is designated as the fourth cross section A4, the cross section of the penetration nozzle 14 is designated as the fifth cross section A5, and the cross section located between the fourth cross section A4 and the fifth cross section A5 is designated as the sixth cross section A6. The penetration outlet portion 16 has the same cross-sectional area and a circular cross-sectional shape throughout the direction in which the penetration axis O2 of the penetration nozzle 4 extends. In other words, the fourth cross section A4, the fifth cross section A5, and the sixth cross section A6 each have the same cross-sectional area. Furthermore, the fourth cross section A4, the fifth cross section A5, and the sixth cross section A6 each have a circular cross-sectional shape. A penetration nozzle 4 having such a penetration outlet portion 16 injects fuel F with a high penetration force into the combustion chamber 101.

[0021] In one embodiment, the cross-sectional area of ​​the fifth cross section A5 of the penetration nozzle 14 is the same as the cross-sectional area of ​​the second cross section A2 of the diffusion nozzle 8. In other words, the penetration nozzle 4 is configured to increase the amount of fuel F supplied to the first region R1 by the magnitude of the penetration force rather than the size of the cross-sectional area. Note that the present disclosure is not limited to the cross-sectional area of ​​the fifth cross section A5 of the penetration nozzle 14 being the same as the cross-sectional area of ​​the second cross section A2 of the diffusion nozzle 8.

[0022] (Operations and Effects) The operations and effects of the fuel injection device 1 according to one embodiment will be described. Depending on the swirl flow, a first region R1 where the amount of air is relatively large and a second region R2 where the amount of air is relatively small may occur within the combustion chamber 101 of an engine. According to one embodiment, the tip portion 6 of the nozzle body 2 includes a diffusion nozzle 3 capable of injecting fuel F with high diffusivity and a through-hole nozzle 4 capable of injecting fuel F with high penetration. Therefore, by arranging the diffusion nozzle 3 and the through-hole nozzle 4 so as to correspond to the regions of different air amounts occurring within the combustion chamber 101, it is possible to further promote mixing of the fuel F and air A injected into the combustion chamber 101. In particular, by positioning the first region R1 in the injection direction Db of the through-hole nozzle 4, it is possible to prevent the fuel F injected from the through-hole nozzle 4 from being supplied to regions other than the first region R1 (such as the second region R2), thereby allowing a large amount of fuel F to be supplied to the first region R1. Furthermore, by ensuring that the first region R1 is not positioned in the injection direction Da of the diffusion nozzle hole 3, the fuel F injected from the diffusion nozzle hole 3 can be diffused and supplied outside the first region R1 (preventing the fuel F from being excessive or insufficient in some areas).

[0023] The through-holes 4 inject fuel F into the combustion chamber 101 with greater penetration than the diffusion holes 3, and are therefore capable of supplying fuel F to spaces in the combustion chamber 101 that are spaced apart from the nozzle body 2. According to one embodiment, the fuel injection device 1 includes a first diffusion hole 3A whose injection direction Da is inclined with respect to the extension direction Dx and that is capable of injecting fuel F with high diffusivity, and a first through-hole 4A whose injection direction Db is along the extension direction Dx and that is capable of injecting fuel F with greater penetration. As a result, the fuel F is widely injected near the tip 6 of the nozzle body 2 within the combustion chamber 101, and the fuel F is supplied to spaces in the combustion chamber 101 that are spaced apart from the tip 6 of the nozzle body 2, thereby further promoting mixing of the fuel F and air A.

[0024] If the diffusion hole 3 is configured so that the cross-sectional area of ​​the diffusion outlet section 10 increases toward the diffusion nozzle hole 8, the flow of the fuel F may separate from the inner wall surface of the diffusion nozzle hole 3, which may result in a decrease in the diffusibility of the fuel F. According to one embodiment, the cross-sectional area of ​​the diffusion outlet section 10 is the same from the inlet 11 to the diffusion nozzle hole 8, so that the increase in the cross-sectional area toward the diffusion nozzle hole 8 is suppressed. Therefore, the occurrence of separation of the fuel F flowing through the diffusion outlet section 10 can be suppressed, and the decrease in the diffusibility of the fuel F injected from the diffusion nozzle hole 3 can be suppressed.

[0025] According to one embodiment, the inlet 11 has a circular shape and the diffusion nozzle 8 has an elliptical shape, so that the diffusion nozzle 3 capable of injecting the fuel F into the combustion chamber 101 with high diffusivity can be easily formed in the tip 6 of the nozzle body 2. Note that the present disclosure does not limit the shape of the diffusion nozzle 8 to an elliptical shape, nor does it limit the shape of the inlet 11 to a circular shape. Any shape, such as a rectangular shape or an oval shape, can be used for each of the diffusion nozzle 8 and the inlet 11.

[0026] According to one embodiment, the penetration outlet portion 16 has a constant cross-sectional area from the penetration inlet 15 to the penetration nozzle 14 and a uniform circular cross-sectional shape, so that a penetration injection hole 4 capable of injecting fuel F with high penetration force can be easily formed in the tip portion 6 of the nozzle body 2. Note that the present disclosure is not limited to the configuration exemplified in the one embodiment as long as the penetration outlet portion 16 is configured so that the cross-sectional area does not increase toward the penetration nozzle 14. In some embodiments, the penetration outlet portion 16 is configured so that the cross-sectional shape changes from the penetration inlet 15 to the penetration nozzle 14 but the cross-sectional area is uniform.

[0027] FIG. 4 is a front view of a nozzle body 2 according to some embodiments, as viewed from the combustion chamber 101. As shown in FIG. 4 , the circumferential direction Dy is the direction around the axis O of the nozzle body 2, and the radial direction Dz is the direction perpendicular to the axis O starting from the axis O of the nozzle body 2. The clockwise direction in the circumferential direction Dy is defined as one side of the circumferential direction Dy, and the counterclockwise direction is defined as the other side of the circumferential direction Dy. The radial direction Dz, which is closer to the axis O, is defined as the inner side of the radial direction Dz, and the radial direction Dz, which is farther away from the axis O, is defined as the outer side of the radial direction Dz. In the configuration illustrated in FIG. 4 , the elliptical shape (second cross section A2) of the diffusion nozzle hole 8 has a major axis L1 extending along the circumferential direction Dy and a minor axis L2 extending along the radial direction Dz. According to the configuration illustrated in FIG. 4 , the fuel F can be widely injected near the tip 6 of the nozzle body 2 within the combustion chamber 101.

[0028] Figure 5 is a diagram illustrating the configuration of the penetration outlet portion 16 of the through-hole injection hole 4 according to several embodiments. In the configuration illustrated in Figure 5, the penetration outlet portion 16 is configured so that the cross-sectional area decreases from the penetration inlet 15 to the penetration nozzle 14, and the cross-sectional shape is constant and circular. The cross-sectional areas increase in the order of the fourth cross section A4, the sixth cross section A6, and the fifth cross section A5. According to the configuration illustrated in Figure 5, the penetration force of the fuel F injected from the through-hole injection hole 4 can be improved.

[0029] <Engine> (Configuration) In some embodiments, the engine provided with the fuel injection device 1 according to the present disclosure is an opposed-piston engine 100. Fig. 6 is a longitudinal cross-sectional view schematically illustrating the configuration of the opposed-piston engine 100 including the fuel injection device 1 according to some embodiments. As illustrated in Fig. 6, the opposed-piston engine 100 includes a cylinder 102, a first piston 104 disposed on one side of the interior of the cylinder 102 (i.e., a cylinder bore 103) in the axial direction D4, a second piston 106 disposed on the other side of the cylinder bore 103 in the axial direction D4, a first fuel injection device 1A(1) disposed on a wall surface 105 of the cylinder 102, and a second fuel injection device 1B(1) disposed on the wall surface 105 of the cylinder 102, shifted in the circumferential direction (see Fig. 10 ) about the axis Os of the cylinder 102 so as to face the first fuel injection device 1A across the axis Os of the cylinder 102.

[0030] 6 , an opposed-piston engine 100 has an intake port 108 formed in a wall surface 105 of a cylinder 102 on one side of the cylinder bore 103 in the axial direction D4, and an exhaust port 110 formed in the wall surface 105 of the cylinder 102 on the other side of the cylinder bore 103 in the axial direction D4. Air A supplied from the intake port 108 to the cylinder bore 103 forms a swirling flow within the cylinder bore 103. The formation of this swirling flow enhances the exchange of intake air and exhaust air within the cylinder bore 103 during the intake stroke and the exhaust stroke.

[0031] The first piston 104 and the second piston 106 reciprocate inside the cylinder 102 so as to reach the closest position (TDC position) and the furthest position (BDC position) at the same time in the cylinder bore 103. The first fuel injection device 1A and the second fuel injection device 1B each inject fuel F into the cylinder bore 103 when the first piston 104 and the second piston 106 reach the TDC position, and the fuel F injected into the cylinder bore 103 ignites in the high-temperature atmosphere inside the cylinder bore 103, forming a flame.

[0032] In the embodiment illustrated in FIG. 6 , a first cavity 104a is formed in the top surface of the first piston 104. The concave surface of the first cavity 104a is concavely curved toward one side in the axial direction D4 as it approaches the axis Os. Similarly, a second cavity 106a is formed in the top surface of the second piston 106. The concave surface of the second cavity 106a is concavely curved toward the other side in the axial direction D4 as it approaches the axis Os. By forming the first cavity 104a and the second cavity 106a, when the first piston 104 and the second piston 106 move away from each other during fuel injection, a diffusion effect toward the outer circumferential region occurs when the piston-to-piston distance is short, thereby further improving the effect of suppressing interference between the fuel F injected from the first fuel injection device 1A and the second fuel injection device 1B. A combustion chamber 101 formed in the cylinder bore 103 is defined by a wall surface 105 of the cylinder 102 , the top surface of the first piston 104 , and the top surface of the second piston 106 .

[0033] The first fuel injection device 1A further includes a second diffusion injection hole 3B(3) and a second through-hole injection hole 4B(4) in addition to the first diffusion injection hole 3A and the first through-hole injection hole 4A described above. Fig. 7 is a cross-sectional view schematically showing the configuration of the first fuel injection device 1A shown in Fig. 6, and is a diagram for explaining the second diffusion injection hole 3B. Fig. 8 is a cross-sectional view schematically showing the configuration of the first fuel injection device 1A shown in Fig. 6, and is a diagram for explaining the second through-hole injection hole 4B. Note that the second fuel injection device 1B has a configuration similar to that of the first fuel injection device 1A, and therefore a detailed description of the configuration will be omitted.

[0034] The injection direction Dc of the second diffusion nozzle hole 3B is perpendicular to the cross section of the diffusion nozzle hole 8 and is the direction of extension of an imaginary line (not shown) passing through the center of this cross section. In the embodiment illustrated in Fig. 7, the second diffusion nozzle hole 3B is formed in the tip portion 6 of the nozzle body 2 so that the injection direction Dc is inclined with respect to the extension direction Dx. Specifically, the second diffusion nozzle hole 3B is formed in the tip portion 6 of the nozzle body 2 so that the second diffusion axis O3 extends linearly and is inclined with respect to the axis O.

[0035] The injection direction Dd of the second through-hole injection hole 4B is perpendicular to the cross section of the through-hole injection hole 14 and is the direction of an imaginary line (not shown) passing through the center of this cross section. In the embodiment shown in Fig. 8, the second through-hole injection hole 4B is formed in the tip 6 of the nozzle body 2 so that the injection direction Dd is more inclined than the injection direction Da of the first diffusion injection hole 3A. Specifically, the second through-hole injection hole 4B is formed in the tip 6 of the nozzle body 2 so that the second penetration axis O4 extends linearly and is more inclined with respect to the axis O than the diffusion axis O1 of the first diffusion injection hole 3A.

[0036] Fig. 9 is a front view of the nozzle body 2 of the first fuel injection device 1A shown in Fig. 6 as viewed from the cylinder bore 103. In the embodiment illustrated in Fig. 9, the second diffusion nozzle 3B is located on the opposite side of the first diffusion nozzle 3A across an imaginary line LA that passes through the center of the through-hole 14 of the first diffusion nozzle 4A and the center of the through-hole 14 of the second diffusion nozzle 4B. The diffusion nozzle 8 of the first diffusion nozzle 3A and the diffusion nozzle 8 of the second diffusion nozzle 3B are each located between the through-hole 14 of the first diffusion nozzle 4A and the through-hole 14 of the second diffusion nozzle 4B in the radial direction Dz. In other words, the through-hole 14 of the second diffusion nozzle 4B is located outward in the radial direction Dz from the diffusion nozzle 8 of the first diffusion nozzle 3A and the diffusion nozzle 8 of the second diffusion nozzle 3B.

[0037] 10 is a diagram showing an example of the injection direction of fuel F injected from the first diffusion nozzle hole 3A, the second diffusion nozzle hole 3B, the first through-hole nozzle hole 4A, and the second through-hole nozzle hole 4B, as viewed from the axial direction D4 of the cylinder bore 103. In FIG. 10, the flow direction of the swirling flow is indicated by the symbol b.

[0038] As described above, a first cavity 104a is formed in the top surface of the first piston 104, and a second cavity 106a is formed in the top surface of the second piston 106. Therefore, the axial dimension D4 of the combustion chamber 101 increases as the combustion chamber approaches the axis Os. Meanwhile, the path through which the swirling flow passes becomes shorter as the combustion chamber approaches the axis Os. As shown in FIG. 10 , the inner path C1 of the swirling flow is shorter than the outer path C2. Therefore, as illustrated in FIG. 10 , a first region R1, where the amount of air is relatively large, is formed in one central portion of the combustion chamber 101 (the center of the radius of the combustion chamber 101), and a second region R2, where the amount of air is small, is formed outside the first region R1. The second region R2 is also formed inside the first region R1.

[0039] 10, the injection direction Da of the first diffusion nozzle hole 3A and the injection direction Dc of the second diffusion nozzle hole 3B are not directed toward the axis Os but are along the flow direction b of the swirl flow. The injection direction Db of the first through-hole nozzle 4A and the injection direction Dd of the second through-hole nozzle 4B are directed toward the axis Os.

[0040] 6, the fuel F injected from each of the first diffusion nozzle hole 3A and the second diffusion nozzle hole 3B can be supplied to the second region R2, and the fuel F injected from each of the first through-hole nozzle hole 4A and the second through-hole nozzle hole 4B can be supplied to the first region R1. This further promotes mixing of the fuel F and air A injected into the combustion chamber 101.

[0041] In the opposed-piston engine 100 illustrated in Fig. 6, the injection direction Da of the first diffusion nozzle hole 3A and the injection direction Dc of the second diffusion nozzle hole 3B are different from each other. Therefore, the first diffusion nozzle hole 3A and the second diffusion nozzle hole 3B supply fuel F to different portions of the second region R2, further promoting the mixing of the fuel F and air A. In the opposed-piston engine 100 illustrated in Fig. 6, the injection direction Db of the first through-through nozzle hole 4A and the injection direction Dd of the second through-through nozzle hole 4B are different from each other. Therefore, the first through-through nozzle hole 4A and the second through-through nozzle hole 4B supply fuel F to different portions of the first region R1, further promoting the mixing of the fuel F and air A.

[0042] The contents described in each of the above embodiments can be understood, for example, as follows.

[0043] [1] A fuel injection device (1) according to the present disclosure is a fuel injection device for injecting fuel (F) into a combustion chamber (101) of an engine, comprising a nozzle body (2) having a plurality of nozzle holes (3, 4) formed at a tip portion (6) that communicate with the combustion chamber and are configured to inject the fuel, and the plurality of nozzle holes include: at least one diffusion nozzle hole (3) that is connected to a diffusion nozzle hole (8) that opens into the combustion chamber and has a diffusion outlet portion (10) configured so that the length of the cross section in a first direction (D1) increases toward the diffusion nozzle hole; and at least one through-hole (4) that is connected to a through-hole (14) that opens into the combustion chamber and has a penetration outlet portion (16) configured so that the cross-sectional area does not increase toward the through-hole hole.

[0044] In the combustion chamber of an engine, regions with a relatively large amount of air and regions with a relatively small amount of air may occur depending on the swirl flow. According to the configuration described in [1] above, the multiple injection holes include diffusion injection holes capable of injecting fuel with high diffusivity and through injection holes capable of injecting fuel with high penetration. Therefore, by arranging the diffusion injection holes and through injection holes so as to correspond to regions with different air amounts occurring in the combustion chamber, it is possible to further promote mixing of the fuel and air injected into the combustion chamber.

[0045] [2] In some embodiments, in the configuration described in [1] above, the diffusion outlet portion is configured such that the length of the diffusion outlet portion in a second direction (D2) perpendicular to the first direction of the cross section decreases toward the diffusion nozzle.

[0046] If the cross-sectional area of ​​the diffusion outlet portion increases toward the diffusion orifice, the flow of fuel may separate from the inner wall surface of the diffusion orifice, which may result in a decrease in the diffusivity of the fuel. According to the configuration described in [2] above, the cross-sectional area of ​​the diffusion outlet portion is prevented from increasing toward the diffusion orifice, thereby preventing a decrease in the diffusivity of the fuel injected from the diffusion orifice.

[0047] [3] In some embodiments, in the configuration described in [2] above, the diffusion nozzle has an elliptical shape, and the inlet (11) of the diffusion outlet portion on the opposite side to the diffusion nozzle has a circular shape.

[0048] According to the configuration described in [3] above, a diffusion nozzle hole capable of injecting highly diffusible fuel can be easily formed near the tip of the nozzle body.

[0049] [4] In some embodiments, in the configuration described in [3] above, the diffusion nozzle has an elliptical shape, and the diffusion outlet portion is configured so that the cross-sectional area is constant from the inlet to the diffusion nozzle.

[0050] According to the configuration described in [4] above, the influence of the change in cross-sectional area on the flow of fuel is suppressed, so that fuel with high diffusibility can be injected from the diffusion injection hole.

[0051] [5] In some embodiments, in the configuration described in [4] above, the elliptical shape of the diffusion nozzle has a major axis (L1) extending along a circumferential direction (Dy) relative to the axis (O) of the nozzle body, and a minor axis (L2) extending along a radial direction (Dz) relative to the axis of the nozzle body.

[0052] According to the configuration described in [5] above, fuel can be widely injected in the vicinity of the tip of the nozzle body within the combustion chamber.

[0053] [6] In some embodiments, in the configuration described in any one of [1] to [5] above, the penetration outlet portion is configured so that the cross-sectional area decreases toward the penetration nozzle, or so that the cross-sectional area is constant and the cross-sectional shape is the same toward the penetration nozzle.

[0054] According to the configuration described in [6] above, a through injection hole capable of injecting fuel with a large penetration force can be easily formed at the tip of the nozzle body.

[0055] [7] In some embodiments, in the configuration described in any one of [1] to [6] above, at least one of the through-holes includes a first through-hole (4A) formed so that the injection direction (Db) is along the extension direction (Dx) in which the axis (O) of the nozzle body extends, and at least one of the diffusion holes includes a first diffusion hole (3A) formed so that the injection direction (Da) is inclined with respect to the extension direction.

[0056] According to the configuration described in [7] above, the fuel injection device includes a first diffusion nozzle hole capable of injecting highly diffusive fuel whose injection direction is inclined with respect to the extension direction, and a first through-hole hole capable of injecting highly penetrating fuel whose injection direction is along the extension direction. This allows the fuel to be widely injected near the tip of the nozzle body within the combustion chamber, and the fuel to be supplied to a space within the combustion chamber separated from the tip of the nozzle body, thereby further promoting the mixing of the fuel and air.

[0057] [8] In some embodiments, in the configuration described in [7] above, at least one of the through-holes includes a second through-hole (4B) formed so that the injection direction (Dd) is more inclined than that of the first diffusion hole.

[0058] According to the configuration described in [8] above, fuel can be supplied to a space different from the first through-hole, and the mixing of fuel and air can be further promoted.

[0059] [9] In some embodiments, in the configuration described in [8] above, at least one of the diffusion nozzle holes is a second diffusion nozzle hole formed so that the injection direction (Dc) is inclined with respect to the extension direction, and includes a second diffusion nozzle hole (3B) located on the opposite side of the first diffusion nozzle hole across an imaginary line (LA) passing through the through-hole of the first through-hole and the through-hole of the second through-hole, and the diffusion nozzle hole of the first diffusion nozzle hole and the diffusion nozzle hole of the second diffusion nozzle hole are each located between the through-hole of the first through-hole and the through-hole of the second through-hole.

[0060] According to the configuration described in [9] above, the fuel can be supplied to a space different from the first diffusion nozzle hole, thereby further promoting the mixing of the fuel and air. Also, the first diffusion nozzle hole and the second diffusion nozzle hole can each inject fuel in a direction along the swirling flow.

[0061]

[10] An engine (100) according to the present disclosure includes: a cylinder (102); a first piston (104) arranged on one side of an axial direction (D4) inside the cylinder; a second piston (106) arranged on the other side of the axial direction inside the cylinder; a first fuel injection device (1A) according to any one of [1] to [9] above, the first fuel injection device being arranged on a wall surface (105) of the cylinder; and a second fuel injection device (1B) according to any one of [1] to [9] above, the second fuel injection device being arranged on the wall surface of the cylinder, shifted circumferentially from the first fuel injection device so as to face each other across the axis (Os) of the cylinder.

[0062] According to the configuration described in

[10] above, it is possible to provide an engine that can further promote the mixing of fuel and air injected into the combustion chamber.

[0063] REFERENCE SIGNS LIST 1 Fuel injection device 1A First fuel injection device 1B Second fuel injection device 2 Nozzle body 3 Diffusion nozzle hole 3A First diffusion nozzle hole 3B Second diffusion nozzle hole 4 Penetration nozzle hole 4A First penetration nozzle hole 4B Second penetration nozzle hole 6 Tip portion 7 Fuel flow path 8 Diffusion nozzle hole 10 Diffusion outlet portion 11 Inlet port 12 Upstream side portion 14 Penetration nozzle hole 15 Penetration inlet port 16 Penetration outlet portion 100 Opposed piston engine 101 Combustion chamber 102 Cylinder 103 Cylinder bore 104 First piston 104a First cavity 105 Cylinder wall surface 106 Second piston 106a Second cavity 108 Air intake port 110 Exhaust port A Air A1 First cross section A2 Second cross section A3 Third cross section A4 Fourth cross section A5 Fifth cross section A6 Sixth cross section D1 First direction D2 Second direction D4 Axial direction Da Injection direction of first diffusion nozzle hole Db Injection direction of first through-hole Dc Injection direction of second diffusion nozzle hole Dd Injection direction of second through-hole Dx Extension direction Dy Circumferential direction Dz Radial direction F Fuel L1 Major axis L2 Minor axis LA Virtual line O Axis O1 Diffusion axis O2 Through-hole axis O3 Second diffusion axis O4 Second through-hole axis Os Axis center R1 First region R2 Second region b Flow direction of swirl flow

Claims

1. A fuel injection device that injects fuel into a combustion chamber of an engine, comprising a nozzle body having a plurality of nozzle holes formed at its tip, the nozzle holes communicating with the combustion chamber and configured to inject the fuel, the plurality of nozzle holes including: at least one diffusion nozzle hole connected to a diffusion nozzle hole opening into the combustion chamber and having a diffusion outlet portion configured so that the length of its cross section in a first direction expands toward the diffusion nozzle hole; and at least one through nozzle hole connected to a through nozzle hole opening into the combustion chamber and having a through outlet portion configured so that the cross-sectional area does not expand toward the through nozzle hole.

2. The fuel injection device according to claim 1, wherein the diffusion outlet portion is configured such that the length of the cross section in a second direction perpendicular to the first direction decreases toward the diffusion nozzle.

3. The fuel injection device according to claim 2, wherein the diffusion nozzle has an elliptical shape, and an inlet of the diffusion outlet portion opposite to the diffusion nozzle has a circular shape.

4. The fuel injection device according to claim 3, wherein the diffusion nozzle has an elliptical shape, and the diffusion outlet portion is configured so that the cross-sectional area is constant from the inlet toward the diffusion nozzle.

5. A fuel injection device according to claim 4, wherein the elliptical shape of the diffusion nozzle hole has a major axis extending in a circumferential direction relative to the axis of the nozzle body and a minor axis extending in a radial direction relative to the axis of the nozzle body.

6. A fuel injection device as claimed in any one of claims 1 to 5, wherein the penetration outlet portion is configured so that its cross-sectional area decreases towards the penetration nozzle, or so that its cross-sectional area is constant and its cross-sectional shape is the same towards the penetration nozzle.

7. A fuel injection device as claimed in any one of claims 1 to 5, wherein at least one of the through injection holes includes a first through injection hole formed so that the injection direction is along the extension direction in which the axis of the nozzle body extends, and at least one of the diffusion injection holes includes a first diffusion injection hole formed so that the injection direction is inclined with respect to the extension direction.

8. A fuel injection device according to claim 7, wherein at least one of the through-holes includes a second through-hole formed so that the injection direction is more inclined than that of the first diffusion hole.

9. A fuel injection device as described in claim 8, wherein at least one of the diffusion nozzles is a second diffusion nozzle formed so that the injection direction is inclined with respect to the extension direction, and includes a second diffusion nozzle located on the opposite side of the first diffusion nozzle across an imaginary line passing through the through-hole of the first through-hole and the through-hole of the second through-hole, and wherein the diffusion nozzle of the first diffusion nozzle and the diffusion nozzle of the second diffusion nozzle are each located between the through-hole of the first through-hole and the through-hole of the second through-hole.

10. An engine comprising: a cylinder; a first piston arranged on one axial side inside the cylinder; a second piston arranged on the other axial side inside the cylinder; a first fuel injection device as set forth in any one of claims 1 to 5, the first fuel injection device being arranged on a wall surface of the cylinder; and a second fuel injection device as set forth in any one of claims 1 to 5, the second fuel injection device being arranged on the wall surface of the cylinder, circumferentially shifted from the first fuel injection device so as to face opposite the axis of the cylinder.

Images