JP2014132166A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine capable of properly injecting fuel to a combustion chamber by injecting fuel in light of influences of a swirl flow differentiated according to an arrival range of fuel spray when the swirl flow is not generated in the combustion chamber.SOLUTION: An internal combustion engine 1 comprises a fuel injection valve 6 for injecting fuel to a combustion chamber E in which a swirl flow is generated. An interval NF3 between two injection holes 611B, 611C for injecting fuel to a region E12, and an interval NF7 between two injection holes 611F, 611G for injecting fuel to a region E14 are set narrower than an interval NF1 between two injection holes 611H, 611A for injecting fuel to a region E11, and an interval NF5 between two injection holes 611D, 611E for injecting fuel to a region E13.

Description

  The present invention relates to an internal combustion engine.

  An internal combustion engine that generates a swirl flow in a combustion chamber is known. Patent Document 1 describes that fuel spray is caused to flow in a swirl direction in a diesel engine. In addition, regarding the setting of the injection hole interval of the fuel injection valve, Patent Document 2 discloses an in-cylinder direct injection internal combustion engine in which the number of injection holes on the side farther from the side closer to the cavity bottom wall surface is increased. It is disclosed. With this configuration, the internal combustion engine achieves a uniform force for lifting the fuel spray over the cavity.

JP 2009-228599 A JP 2005-163632 A

  For example, the internal combustion engine may have a configuration in which the bottom wall surface of the cylinder head has a pent roof shape and the bottom wall surface of the cavity has a raised shape in accordance with the pent roof shape in the following cases. That is, it is possible to adopt a configuration in which cylinder heads are made common or improved in common between a compression ignition type internal combustion engine (for example, a diesel engine) and a spark ignition type internal combustion engine (for example, a gasoline engine).

  In this case, due to the relationship between the cavity bottom wall surface and the cylinder head bottom wall surface, the injection directions of the plurality of nozzle holes are set as follows. That is, the arrival distance of the fuel spray injected from any one of the plurality of injection holes, and the arrival distance of the fuel spray when no swirl flow is generated in the combustion chamber is the plurality of injection holes It is set so that they are not the same between each other.

  However, when the reaching distance is not the same among the plurality of nozzle holes, the influence of each fuel spray injected from the plurality of nozzle holes from the swirl flow is not the same. For this reason, in this case, it is desired to perform fuel injection in consideration of the influence of the swirl flow that varies depending on the reach distance.

  In view of the above problems, the present invention can appropriately inject fuel into a combustion chamber by performing fuel injection in consideration of the influence of the swirl flow that varies depending on the reach of the fuel spray when no swirl flow is generated in the combustion chamber. An object is to provide an internal combustion engine.

  The present invention includes a fuel injection valve that injects fuel into a combustion chamber in which a swirl flow is generated, and is an injection hole interval between two adjacent injection holes among a plurality of injection holes provided in the fuel injection valve, When the swirl flow is not generated in the combustion chamber, a plurality of nozzle holes provided in the fuel injection valve have a nozzle hole interval between two nozzle holes for injecting fuel into a region where the fuel spray reach distance is set to be relatively long. Of the two nozzle holes adjacent to each other, and two injections for injecting fuel to a region where the fuel spray reach distance is set relatively short when a swirl flow is not generated in the combustion chamber The internal combustion engine is set to be narrower than the interval between the nozzle holes.

  The present invention includes a piston provided with a cavity that is exposed to the combustion chamber, and a cylinder head having a central portion that is a portion that forms the combustion chamber, and the cavity is in a direction along the flow of the swirl flow. A cavity bottom wall surface having a shape whose height changes, and a head bottom wall surface having a shape whose height changes in the direction along the flow of the swirl flow, the central axis of the combustion chamber The distance between the arrival point of fuel spray injected by any one of the plurality of nozzle holes and at least one of the cavity bottom wall surface and the head bottom wall surface is a distance in a direction along It can be set as the structure by which the injection direction of each said several nozzle hole is set so that it may become constant between each nozzle hole.

  According to the present invention, the fuel can be appropriately injected into the combustion chamber by performing the fuel injection in consideration of the influence of the swirl flow that varies depending on the arrival distance of the fuel spray when the swirl flow is not generated in the combustion chamber.

It is a schematic block diagram of an internal combustion engine. It is the figure which looked at the internal combustion engine in the AA cross section shown in FIG. It is a figure which shows a nozzle hole part. It is an external view of a piston. It is a top view of a piston. It is the figure which looked at the piston in the BB cross section shown in FIG. It is the figure which looked at the piston in CC cross section shown in FIG. It is a figure which shows the change of various parameters. It is explanatory drawing of the bottom wall surface according to FIG. It is explanatory drawing of the combustion chamber according to FIG. 8, FIG. It is arrangement | positioning explanatory drawing of a some nozzle hole. It is explanatory drawing of an injection angle. It is the 1st explanatory view of a reaching point. It is explanatory drawing of reachable distance. It is explanatory drawing of a nozzle hole space | interval. It is the 2nd explanatory view of a reaching point. It is a figure which shows an example of the modification of a reference | standard space | interval. It is explanatory drawing of the cross-sectional area of a combustion chamber.

  Embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of an internal combustion engine 1. FIG. 2 is a view of the internal combustion engine 1 taken along the line AA shown in FIG. In FIG. 1, the cylinder block 2 and the cylinder head 3 of the internal combustion engine 1 are shown in a cross section including a central axis P <b> 1 that is the central axis of the combustion chamber E. As for the vertical direction in the internal combustion engine 1, it is assumed that the direction along the central axis P <b> 1 is the vertical direction as shown in FIG. A direction X shown in FIGS. 1 and 2 indicates the intake and exhaust directions of the internal combustion engine 1. A direction Y shown in FIG. 2 indicates the front and rear directions of the internal combustion engine 1. In FIG. 1 and FIG. 2, each configuration is shown in a simplified manner.

  The internal combustion engine 1 is a compression ignition type internal combustion engine, and is an internal combustion engine in which a swirl flow is generated in the combustion chamber E. The internal combustion engine 1 includes a cylinder block 2, a cylinder head 3, an intake valve 4, an exhaust valve 5, a fuel injection valve 6, and a piston 7. A cylinder 21 is formed in the cylinder block 2. The cylinder 21 has a central axis P1. In other words, the cylinder 21 determines the central axis P1. A piston 7 is accommodated in the cylinder 21. A cylinder head 3 is fixed to the upper part of the cylinder block 2.

  The cylinder head 3 forms a combustion chamber E together with the cylinder block 2 and the piston 7. The central part 31 which is a part which forms the combustion chamber E among the bottom wall parts of the cylinder head 3 has a pent roof shape. Specifically, the pent roof shape has a bottom wall surface 311 provided in the central portion 31. The bottom wall surface 311 corresponds to the head bottom wall surface.

  Specifically, the pent roof shape has a top portion at a position offset in the direction X from the central axis P1 to the exhaust side. The central portion 31 (specifically, the bottom wall surface 311) may have a pent roof shape in which the top portion is provided in the direction X in accordance with the central axis P1 or at a position offset from the central axis P1 toward the intake side.

  An intake port 32 and an exhaust port 33 are formed in the cylinder head 3. An intake valve 4 and an exhaust valve 5 are provided. Both the intake port 32 and the exhaust port 33 are open to the combustion chamber E. The intake port 32 guides intake air to the combustion chamber E, and the exhaust port 33 exhausts the gas in the combustion chamber E. The intake valve 4 opens and closes the intake port 32, and the exhaust valve 5 opens and closes the exhaust port 33.

  Specifically, a plurality (two in this case) of intake ports 32 are provided for the combustion chamber E together with the intake valve 4. A plurality (two in this case) of exhaust ports 33 are provided for the combustion chamber E together with the exhaust valve 5. Each intake port 32 may be an independent port that is independent from each other, or may be a part of a siamese port that is branched into the combustion chamber E and opened in the middle. The specific shape of each intake port 32 may be different from each other. The same applies to each exhaust port 33.

  The cylinder head 3 is further provided with a fuel injection valve 6. The fuel injection valve 6 injects fuel into the combustion chamber E. The fuel injection valve 6 includes a nozzle hole 61. The nozzle hole 61 is exposed at the center of the upper part of the combustion chamber E. The position along the direction X of the fuel injection valve 6 is set in accordance with the top of the pent roof shape that the central portion 31 has. Therefore, specifically, the fuel injection valve 6 is provided at a position offset in the direction X from the central axis P1 to the exhaust side.

  FIG. 3 is a view showing the nozzle hole 61. The nozzle hole 61 is provided with a nozzle hole 611. The nozzle hole 61 is a part of the fuel injection valve 6 where the nozzle hole 611 is provided, and has a central axis P2. The nozzle hole 61 is specifically the tip of the nozzle body provided in the fuel injection valve 6. A plurality (eight here) of the nozzle holes 611 are provided along the circumferential direction of the nozzle hole portion 61. The number of the plurality of nozzle holes 611 can be an even number.

  FIG. 4 is an external view of the piston 7. FIG. 5 is a top view of the piston 7. FIG. 6 is a view of the piston 7 taken along the line BB shown in FIG. FIG. 7 is a view of the piston 7 as seen in the CC cross section shown in FIG. 4 to 7 indicate the direction of the piston 7 in the internal combustion engine 1 by displaying the intake side, the exhaust side, the front side, and the rear side in addition to the vertical direction, the direction X, and the direction Y in the internal combustion engine 1 described above. In the following description, the piston 7 will be described while also considering the state in the internal combustion engine 1. For this reason, also in the description shown below, the piston 7 will be described according to these indications as necessary.

  The piston 7 includes a cavity 71. The cavity 71 is provided at the top of the piston 7. For this reason, the cavity 71 is exposed to the combustion chamber E in the internal combustion engine 1. The position along the direction X of the cavity 71 is set according to the fuel injection valve 6. For this reason, the cavity 71 is provided at a position offset from the central axis P3, which is the central axis of the piston 7, to the exhaust side in the direction X. The piston 7 is provided in the internal combustion engine 1 so that the central axis P3 is disposed at the same position as the central axis P1. The same thing includes the case where they differ from each other within the range of manufacturing error. The same thing can include the case where it is different within the range which can show | play the effect of this invention further. The same applies to the following.

  The cavity 71 includes a peripheral edge portion 711, a bottom wall surface 712, and an intermediate portion 713. The peripheral edge 711 has a cylindrical shape. The peripheral edge 711 is not necessarily limited to a cylindrical shape, and may have a cylindrical shape such as an ellipse, for example. The peripheral edge 711 has a central axis P4 that is the central axis of the cavity 71. In other words, the peripheral edge 711 determines the central axis P4.

  The central axis P4 extends along the central axis P3. The central axis P4 also corresponds to the rotational central axis of the swirl flow in the cavity 71. The central axis P4 is set at a position offset in the direction X to the exhaust side from the central axis P3. Specifically, the central axis P4 is set to be disposed at the same position as the central axis P2 in the internal combustion engine 1.

  The bottom wall surface 712 has a raised shape. The shape is axisymmetric with respect to the central axis P3 and is symmetrical with respect to the central axis P4. The bottom wall surface 712 shares the peripheral edge 711 and the central axis P4. The bottom wall surface 712 does not necessarily have to share the peripheral edge 711 and the central axis P4. The bottom wall surface 712 corresponds to the cavity bottom wall surface. The intermediate portion 713 is provided between the peripheral edge portion 711 and the bottom wall surface 712 and connects the peripheral edge portion 711 and the bottom wall surface 712. The intermediate portion 713 includes an adjacent portion A adjacent to the bottom wall surface 712.

  Specifically, the bottom wall surface 712 is adjacent to each other on each side of the piston 7 including the central axis P4 (for example, the cross section shown in FIG. 6 or 7) with the central axis P4 interposed therebetween. It is provided so as to protrude from the height at which the part A is provided. In each cross section of the piston 7 including the central axis P4, the heights of the adjacent portions A sandwiching the central axis P4 are specifically the same.

  In each of the cross sections, each of the adjacent portions A sandwiching the central axis P4 is more specifically the portion of the surface of the cavity 71 having the lowest position. Among the cross sections, the height of each of the adjacent portions A sandwiching the central axis P4 is higher in the cross section shown in FIG. 7 than in the cross section shown in FIG. In each cross section of the piston 7 including the central axis P4, the heights of the adjacent portions A with the central axis P4 interposed therebetween are not necessarily the same.

  Next, the bottom wall surface 712 will be further described with reference to FIGS. FIG. 8 is a diagram showing changes in various parameters. FIG. 9 is an explanatory diagram of the bottom wall surface 712 corresponding to FIG. FIG. 10 is an explanatory diagram of the combustion chamber E according to FIGS. The vertical axis | shaft shown in FIG. 8 shows the position in the direction along the central axis P1. The horizontal axis shown in FIG. 8 indicates the phase (angular position) with the central axis P4 as the rotation center. The direction R shown in FIGS. 9 and 10 indicates the rotational direction of the swirl flow.

  FIG. 8 shows the height H1 and the height H2 as various parameters. The height H1 is the height of the bottom wall surface 712. Specifically, the height H1 is based on a virtual plane L (see FIGS. 6 and 7) orthogonal to the central axis P4 and positioned below the bottom wall surface 712. That's it. The height H2 is the height of the bottom wall surface 311. Specifically, the height H2 is a height based on a virtual plane (here, the virtual plane L) orthogonal to the central axis P1 and positioned below the bottom wall surface 311. is there. FIG. 8 also shows an increase portion D1, a decrease portion D2, and an intermediate portion D3, which will be described later, and regions E1 to E8, which will be described later.

  The changes in various parameters shown in FIG. 8 are changes in the direction along the flow of the swirl flow. The phase M1 indicates the phase center on the front side in the phase with the central axis P4 as the rotation center. The phase M2 is the exhaust side of the phase, the phase M3 is the rear side of the phase, and the phase M4 is the intake side of the phase center. Specifically, the change in the direction along the flow of the swirl flow means the following change. That is, the locus of the swirl flow in the cavity 71 corresponds to the shape of the peripheral edge 711.

  For this reason, the change in the direction along the flow of the swirl flow means a change in the direction along the outline of the peripheral edge portion 711. This change is specifically a change according to the phase centered on the central axis P4 and a change recognized along the swirl flow virtual locus C (see FIG. 10) according to the shape of the peripheral edge 711. It means that. Specifically, the virtual locus C is a ring-shaped locus that shares the peripheral axis 711 and the central axis P4 and is similar to the outline of the peripheral edge 711 viewed along the central axis P4.

  The bottom wall surface 712 has a shape in which the height H1 changes in the direction along the flow of the swirl flow. Specifically, the bottom wall surface 712 is a bottom wall surface having a decreasing portion D1, an increasing portion D2, and an intermediate portion D3 described below.

  The decreasing portion D1 is provided in a section from the phase M1 to the phase M2 along the direction R and in a section from the phase M3 to the phase M4 along the direction R. The decrease part D11 indicates that the decrease part D1 is provided in the former section, and the decrease part D12 indicates that the decrease part D1 is provided in the latter section. The decreasing portion D1 is a portion where the height H1 decreases along the direction R.

  The increasing portion D2 is provided in a section from the phase M2 to the phase M3 along the direction R and in a section from the phase M4 to the phase M1 along the direction R. The increase part D21 indicates that it is an increase part D2 provided in the former section, and the increase part D22 indicates that it is an increase part D2 provided in the latter section. The increasing portion D2 is a portion where the height H1 increases along the direction R.

  The intermediate portion D3 is provided corresponding to each of the phase M1, the phase M2, the phase M3, and the phase M4. The intermediate part D31 is an intermediate part D3 provided in correspondence with the phase M1. The intermediate part D32 corresponds to the phase M2, the intermediate part D33 corresponds to the phase M3, and the intermediate part D34 corresponds to the intermediate part D3 provided corresponding to the phase M4. The intermediate portion D3 is adjacent to the decrease portion D1 and the increase portion D2 in the direction along the direction R, and connects the adjacent decrease portion D1 and increase portion D2. The intermediate portion D3 is a portion where the height H1 is constant in the direction along the flow of the swirl flow.

  The intermediate portion D3 may be an inflection portion that changes the change tendency of the height H1 between the adjacent decrease portion D1 and increase portion D2. The bottom wall surface 712 may have an edge portion formed by, for example, the decreasing portion D1 and the increasing portion D2 that are adjacent to each other instead of including the intermediate portion D3.

  The top of the bottom wall surface 712 is flat. Therefore, specifically, the bottom wall surface 712 has a shape in which the height H1 changes in a direction along the flow of the swirl flow in a portion other than the top portion. Similarly to the bottom wall surface 712, the surface of the intermediate portion 713 includes a decrease portion D1, an increase portion D2, and an intermediate portion D3. The bottom wall surface 712 can further be a portion including the surface of the intermediate portion 713. That is, the surfaces of the bottom wall surface 712 and the intermediate portion 713 can be the cavity bottom wall surface.

  The bottom wall surface 311 also has a shape in which the height H2 changes in the direction along the flow of the swirl flow. On the other hand, the height H1 changes similarly to the height H2 in the direction along the flow of the swirl flow. This is because the bottom wall surface 712 is provided so that the cross-sectional area of the combustion chamber E including the central axis P4 is substantially constant in the direction along the flow of the swirl flow when the position of the piston 7 is fixed. It is. In other words, this is because the bottom wall surface 712 is provided so as to suppress the change in the cross-sectional area in the direction along the flow of the swirl flow.

  The combustion chamber E has a plurality of regions E1 to E8. Regions E <b> 1 to E <b> 8 exist on the cavity 71. The region E1 is a region adjacent to the intermediate part D31. The region E2 is in the decrease portion D11, the region E3 is in the intermediate portion D32, the region E4 is in the increase portion D21, the region E5 is in the intermediate portion D33, the region E6 is in the decrease portion D12, the region E7 is in the intermediate portion D34, and the region E8. Are regions adjacent to the increasing portion D22.

  The region E4 and the region E8 are regions in which the swirl flow circulates while being swung, as a result of the swirl flow flowing while being affected by the increased portion D2. The region E4 and the region E8 are regions in which the fuel spray is easily transported to the bottom wall surface 311 side of the bottom wall surface 311 and the bottom wall surface 712 as the swirl flow circulates upward while swirling.

  The region E2 and the region E6 are regions in which the swirl flow circulates while being swirled as a result of the swirl flow being circulated while being affected by the reduced portion D1. The region E2 and the region E6 are regions in which the fuel spray is easily transported to the bottom wall surface 712 side of the bottom wall surface 311 and the bottom wall surface 712 as the swirl flow circulates downward while swirling.

  FIG. 11 is an explanatory view of the arrangement of the plurality of nozzle holes 611. FIG. 12 is an explanatory diagram of the injection angle α. In FIG. 11 and FIG. 12, the nozzle hole 611 is indicated by its central axis. In FIG. 12, the injection angle α will be described using the main part of the internal combustion engine 1 shown in the same cross section as the DD cross section shown in FIG. 11. FIG. 12 also shows the reference injection angle αs, the reference arrival point Ns, and the reference distance NLs.

  The plurality of nozzle holes 611 are provided corresponding to the region E2, the region E4, the region E6, and the region E8. The injection holes 611A and 611B indicate the injection holes 611 that inject fuel into the region E2. The injection hole 611C and the injection hole 611D indicate the region E4, the injection hole 611E and the injection hole 611F indicate the region E6, and the injection hole 611G and the injection hole 611H indicate the injection hole 611 that injects the fuel to the region E8.

  The nozzle hole 611A indicates the nozzle hole 611 located on the near side in the direction R from the nozzle hole 611B. The nozzle hole 611C is a nozzle hole 611D, the nozzle hole 611E is a nozzle hole 611F, the nozzle hole 611G is a nozzle hole 611 located on the near side along the direction R from the nozzle hole 611H.

  The injection angle α is any one of the plurality of nozzle holes 611. Specifically, any one of the plurality of nozzle holes 611 has an injection direction that is a central axis P2 or a straight line parallel to the central axis P2. It is an acute angle. The injection angle α5 indicates the injection hole 611E, and the injection angle α8 indicates the injection angle α corresponding to the injection hole 611H. Although not shown, the injection hole 611A has an injection angle α1, the injection hole 611B has an injection angle α2, the injection hole 611C has an injection angle α3, the injection hole 611D has an injection angle α4, the injection hole 611F has an injection angle α6, The nozzle holes 611G each have an injection angle α7 as an injection angle α.

  The reference injection angle αs is an injection angle when no swirl flow is generated in the combustion chamber E, and is specifically set as follows. That is, the reference injection angle αs is set so that any one of the plurality of nozzle holes 611 is positioned at the center between the bottom wall surface 311 and the bottom wall surface 712 in a state where the piston 7 is fixed at the reference position. The In setting the reference injection angle αs in this way, the reference injection angle αs can be set more specifically as follows.

  That is, the reference injection angle αs is a point between the bottom wall surface 311 and the bottom wall surface 712 in the direction along the central axis P1 (that is, the direction along the vertical direction in the internal combustion engine 1 in other words). It can be set to be located at the center between. Alternatively, the reference injection angle αs is a point between the bottom wall surface 311 and the bottom wall surface 712 in a direction perpendicular to the center axis on a plane parallel to the center axis P1 including the center axis. It can be set to be centered.

  Of the above settings, the latter setting is a stricter setting than the former setting, and the former setting is a simpler setting than the latter setting. That is, the reference injection angle αs may be set by a simple setting such as the former setting, or may be set by a strict setting such as the latter setting.

  The reference position can be the position of the piston 7 at the time of fuel injection when the operation state (for example, the rotation speed and load) of the internal combustion engine 1 is in a predetermined operation region. The reference injection angle αs is individually set for each of the plurality of nozzle holes 611. The specific magnitude | size of the reference | standard injection angle (alpha) s does not need to be the same between each of the some nozzle holes 611. FIG.

  The reference reaching point Ns is a fuel spray reaching point when no swirl flow is generated in the combustion chamber E, and is specifically the following reaching point. That is, the reference arrival point Ns is the arrival point of the fuel spray injected by the nozzle hole 611 having the reference injection angle αs in a state where the piston 7 is fixed at the reference position. Specifically, the reference reaching point Ns is a point included in the central axis of the nozzle hole 611. Further, the reference arrival point Ns includes a virtual locus C and is a point where a virtual cylindrical body C ′ extending along the central axis P1 is a destination of fuel spray. The reference arrival point Ns may be a point where the peripheral portion 711 is a destination of fuel spray.

  One of the injection holes 611 (specifically, the injection direction in the vertical direction) is the injection direction indicated by the injection angle α. Moreover, the reference direction corresponding to one of the injection directions among the plurality of injection holes 611 is the injection direction indicated by the reference injection angle αs.

  The reference distance NLs is an arrival distance of the fuel spray from any of the plurality of nozzle holes 611 to the corresponding reference arrival point Ns. Therefore, the reference distance NLs is the fuel spray reach distance when no swirl flow is generated in the combustion chamber E. The specific size of the reference distance NLs may not be the same among the plurality of nozzle holes 611.

  As described above, the nozzle hole 611H injects fuel into the region E8. As described above, the region E8 is a region in the combustion chamber E where the swirl flow circulates upward while swirling. On the other hand, the injection angle α8 is set smaller than the reference injection angle αs. Therefore, the injection direction of the nozzle hole 611H is set to a direction below the reference direction. The same applies to the injection directions of the injection hole 611C, the injection hole 611D, and the injection hole 611G.

  As described above, the nozzle hole 611E injects fuel into the region E6. As described above, the region E6 is a region in the combustion chamber E where the swirl flow circulates downward while swirling. On the other hand, the injection angle α5 is set larger than the reference injection angle αs. Therefore, the injection direction of the nozzle hole 611E is set in a direction above the reference direction. The same applies to the injection directions of the injection hole 611A, the injection hole 611B, and the injection hole 611F.

  FIG. 13 is a first explanatory diagram of the reaching point N. FIG. In FIG. 13, the reaching point N will be described using the main part of the internal combustion engine 1 shown in the same cross section as the DD cross section shown in FIG. 11. FIG. 13 also shows the arrival point N ′ and the arrival distance NL.

  The reaching point N is a point at which fuel spray injected from any of the plurality of nozzle holes 611 arrives. Specifically, the arrival point N is a plurality of nozzle holes 611 when the operation state of the internal combustion engine 1 is in a predetermined operation state (any operation state) among the operation states included in the predetermined operation region described above. The fuel spray which one of them injects reaches. The arrival point N5 indicates the injection hole 611E, and the arrival point N8 indicates the arrival point N corresponding to the injection hole 611H. The arrival point N ′ is a point included in any one of the plurality of nozzle holes 611. The arrival point N5 ′ indicates the injection hole 611E, and the arrival point N8 ′ indicates the arrival point N ′ corresponding to the injection hole 611H.

  For each of the plurality of nozzle holes 611, the arrival point N is specifically the point where the fuel spray that reaches the arrival point N ′ when the swirl flow is not generated in the combustion chamber E is actually reached while being affected by the swirl flow. It has become. Therefore, the reaching point N actually exists in a phase different from that of the cross section shown in FIG. 13 by the swirl flow along the direction R. The reaching point N and the reaching point N ′ are points where the virtual cylindrical body C ′ is the destination of the fuel spray. The arrival point N and the arrival point N ′ may be points where the peripheral portion 711 is a destination of fuel spray.

  The arrival distance NL is the arrival distance of the fuel spray from any one of the plurality of nozzle holes 611 to the corresponding arrival point N ′. Accordingly, the reach distance NL is the reach distance of the fuel spray when no swirl flow is generated in the combustion chamber E. The specific size of the reaching distance NL does not have to be the same among the plurality of nozzle holes 611.

  FIG. 14 is an explanatory diagram of the reach distance NL. FIG. 15 is an explanatory diagram of the interval NF. In FIG. 14, the vertical axis indicates the reach distance, and the horizontal axis indicates the phase with the central axis P4 as the rotation center. In FIG. 14, the region E1 to the region E8, the nozzle hole 611A to the nozzle hole 611H, the curve CNLs, and the region E11 to the region E14 are shown together. In FIG. 15, the region E1 to the region E8, the region E11 to the region E14, the nozzle hole 611A to the nozzle hole 611H, and the reference interval NFs are shown together. 14 and 15, each of the plurality of nozzle holes 611 is indicated by its central axis.

  A curve CNLs indicates a virtual curve of the reference distance NLs. Specifically, the curve CNLs indicates the reference distance NLs corresponding to each of the nozzle holes 611 virtually arranged so that the phase of the central axis coincides with each phase. Regions E11 and E13 indicate regions where the reference distance NLs is set relatively short. Regions E12 and E14 indicate regions where the reference distance NLs is set relatively long. The region E11 and the region E13 may be regions where the reach distance NL is set to be relatively short. At the same time, the region E12 and the region E14 may be regions where the reach distance NL is set relatively long. Each of the region E11 to the region E14 can be a region including each boundary region with an adjacent region.

  The interval NF is a nozzle hole interval between two adjacent nozzle holes among the plurality of nozzle holes 611. Specifically, the interval NF is a phase interval with the central axis P2 as the rotation center. An interval NF1 indicates an interval NF between the nozzle holes 611H and 611A. The distance NF2 is between the nozzle holes 611A and 611B, the distance NF3 is between the nozzle holes 611B and 611C, the distance NF4 is between the nozzle holes 611C and 611D, the distance NF5 is between the nozzle holes 611D and 611E, and the distance NF6 is the nozzle hole 611E. , 611F, the interval NF7 indicates the interval between the nozzle holes 611F and 611G, and the interval NF8 indicates the interval NF between the nozzle holes 611G and 611H.

  The reference interval NFs is a nozzle hole interval when a swirl flow is not generated in the combustion chamber E. Specifically, the nozzle hole interval follows each of the fuel sprays injected from the plurality of nozzle holes 611 along the flow of the swirl flow. The nozzle hole intervals are set so as to be evenly arranged in the direction. For this reason, the reference intervals NFs are specifically equal to each other.

  The reference intervals NFs corresponding to any two intervals among the intervals NF (for example, the reference interval NFs corresponding to the interval NF1 and the reference interval NFs corresponding to the interval NF2) may be different from each other. When the reference intervals NFs are not the same, the correspondence between the reference intervals NFs and the intervals NF can be grasped as follows.

  That is, in this case, when setting the reference interval NFs, the straight line connecting the phase M1 and the phase M3 and the plane including the central axis P2 and the straight line connecting the phase M2 and the phase M4 as viewed along the central axis P2. The plurality of nozzle holes 611 are arranged so as to be symmetrical with respect to each plane including the central axis P2.

  The arrangement of the plurality of nozzle holes 611 arranged in this way is specifically one of the following first and second arrangements. The first arrangement is an arrangement in which the phase of any central axis of the plurality of nozzle holes 611 is set to any one of the phase M1, the phase M2, the phase M3, and the phase M4. The second arrangement is an arrangement in which the phase of the central axis of each of the plurality of nozzle holes 611 is set to a phase other than the phase M1, the phase M2, the phase M3, and the phase M4.

  When each of the reference intervals NFs is not the same, the correspondence between each of the reference intervals NFs and each of the intervals NF depends on one of the first and second arrangements (here, the second arrangement). This can be grasped by comparing each of the reference intervals NFs and each of the intervals NF. In selecting one of the first and second arrangements, an arrangement closer to the arrangement of each of the plurality of nozzle holes 611 in which the intervals NF are set can be selected. The same applies to a case where a plurality of first arrangements and second arrangements are conceivable.

  Since the region E2 and the region E6 are regions in which the swirl flow circulates downward while rotating as described above, each of the corresponding nozzle holes 611 (specifically, the nozzle holes 611A) among the plurality of nozzle holes 611. In each of the nozzle hole 611B, the nozzle hole 611E, and the nozzle hole 611F), the injection direction is a region that is set in a direction higher than the reference direction. Therefore, each of the region E2 and the region E6 is a region where the reaching distance NL is set shorter than the reference distance NLs in each of the corresponding nozzle holes 611 among the plurality of nozzle holes 611.

  Since the region E4 and the region E8 are regions where the swirl flow circulates upward while rotating as described above, each of the corresponding nozzle holes 611 among the plurality of nozzle holes 611 (specifically, the nozzle holes 611C). In each of the nozzle hole 611D, the nozzle hole 611G, and the nozzle hole 611H), the injection direction is a region set in a direction lower than the reference direction. Therefore, each of the region E4 and the region E8 is a region where the reaching distance NL is set longer than the reference distance NLs in each of the corresponding nozzle holes 611 among the plurality of nozzle holes 611.

  The injection hole 611B and the injection hole 611C are injection holes in the region E12, and the injection hole 611F and the injection hole 611G are injection holes in the region E14. The arrival distance NL is smaller between the nozzle hole 611B and the nozzle hole 611C than the nozzle hole 611C. The same applies to the nozzle hole 611F and the nozzle hole 611G.

  The injection hole 611H and the injection hole 611A are injection holes in the area E11, and the injection hole 611D and the injection hole 611E are injection holes in the area E13. The arrival distance NL is larger between the nozzle hole 611H and the nozzle hole 611A than the nozzle hole 611A at the nozzle hole 611H positioned in the foreground along the rotation direction R. The same applies to the nozzle holes 611D and 611E.

  Each of the interval NF3 corresponding to the region E12 and the interval NF7 corresponding to the region E14 is set to be narrower than the reference interval NFs. Each of the interval NF1 corresponding to the region E11 and the interval NF5 corresponding to the region E13 is set wider than the reference interval NFs. For this reason, the interval NF3 and the interval NF7 are set narrower than the interval NF1 and the interval NF5, respectively.

  The region E2 and the region E6 are regions set such that the reference distance NLs increases along the direction R due to the relationship between the bottom wall surface 712 and the bottom wall surface 311. The region E2 and the region E6 may be regions that are set so that the reach distance NL increases along the direction R. Between the region E2 and the region E6, there are two regions, a region including the region E4 and a region including the region E8. Specifically, these two regions are regions along the direction R from region E3 to region E5, and region from region E7 to region E1.

  The region E4 and the region E8 are regions that are set such that the reference distance NLs decreases along the direction R due to the relationship between the bottom wall surface 712 and the bottom wall surface 311. The region E4 and the region E8 may be regions that are set such that the reach distance NL decreases along the direction R. Between the region E4 and the region E8, there are two regions, a region including the region E2 and a region including the region E6. Specifically, these two regions are regions from region E1 to region E3 and region from region E5 to region E7 along direction R.

  Each of the interval NF4 and the interval NF8 corresponding to each of the regions between the region E2 and the region E6 is set to be narrower than the reference interval NFs. Each of the interval NF2 and the interval NF6 corresponding to each of the regions between the region E4 and the region E8 is set wider than the reference interval NFs. For this reason, the interval NF4 and the interval NF8 are set narrower than the interval NF2 and the interval NF6, respectively.

  FIG. 16 is a second explanatory diagram of the arrival point N. FIG. The vertical axis indicates the position in the direction along the central axis P1. The horizontal axis indicates the phase with the central axis P4 as the rotation center. FIG. 16 also shows the height H1, the height H2, the curve CN, the reaching point N ′, the distance F1, and the distance F2. FIG. 16 shows the change in the direction along the flow of the swirl flow according to the phase as in FIG.

  The arrival point N1 is in the injection hole 611A, the arrival point N2 is in the injection hole 611B, the arrival point N3 is in the injection hole 611C, the arrival point N4 is in the injection hole 611D, the arrival point N6 is in the injection hole 611F, and the arrival point N7 is in the injection Reaching points N corresponding to the holes 611G are shown respectively.

  The arrival point N1 ′ is at the injection hole 611A, the arrival point N2 ′ is at the injection hole 611B, the arrival point N3 ′ is at the injection hole 611C, the arrival point N4 ′ is at the injection hole 611D, the arrival point N6 ′ is at the injection hole 611F, The reaching point N7 ′ indicates the reaching point N ′ corresponding to the nozzle hole 611G.

  The distance F1 is a distance in the direction along the central axis P1 and is a distance between the arrival point N and the bottom wall surface 712. The distance F11 is the arrival point N1, the distance F12 is the arrival point N2, the distance F13 is the arrival point N3, the distance F14 is the arrival point N4, the distance F15 is the arrival point N5, the distance F16 is the arrival point N6, and the distance F17. Indicates the arrival point N7, and the distance F18 indicates the distance F1 corresponding to the arrival point N8.

  The distance F2 is a distance in the direction along the central axis P1, and is a distance between the arrival point N and the bottom wall surface 311. The distance F21 is the arrival point N1, the distance F22 is the arrival point N2, the distance F23 is the arrival point N3, the distance F24 is the arrival point N4, the distance F25 is the arrival point N5, the distance F26 is the arrival point N6, and the distance F27. Indicates the arrival point N7, and the distance F28 indicates the distance F2 corresponding to the arrival point N8.

  Curves CN indicated by broken lines are positions in the direction along the central axis P1, and are portions of the bottom wall surface 712 and / or the bottom wall surface 311 (here, the bottom wall surface 712) in the direction along the flow of the swirl flow. It is a virtual curve which shows each position along a shape. Specifically, the partial shape has a ring shape.

  Each injection angle α (in other words, the injection direction of each of the plurality of nozzle holes 611) is a portion of the bottom wall surface 712 in the direction along the flow of the swirl flow in the direction along which the arrival point N is along the flow of the swirl flow. The shape is set so as to be arranged along a partial shape facing each other in the direction along the central axis P1. For this reason, each reaching point N can be included in the curve CN. Specifically, each of the thus set injection angles α is set such that the distance F1 is constant among the plurality of injection holes 611.

  Each of the injection angles α is a partial shape in the direction along the flow of the swirl flow of at least one of the bottom wall surface 712 and the bottom wall surface 311 in the direction along which the arrival point N is along the flow of the swirl flow, It can set so that it may arrange | position along the partial shape which opposes in the direction along the axis line P1. Specifically, each of the injection angles α can be set such that at least one of the distance F1 and the distance F2 is constant between the plurality of injection holes 611. The injection angle α may be set so that the distance F1 and the distance F2 are equal for each of the plurality of nozzle holes 611.

  Next, main effects of the internal combustion engine 1 will be described. Here, in the internal combustion engine 1, the influence of the swirl flow on the fuel spray varies depending on the reach distance NL as follows. That is, in the region E12, the injection distance NL of the nozzle hole 611B positioned in the foreground along the rotation direction R is smaller than the nozzle hole 611C. For this reason, the amount transported by the swirl flow until the injected fuel spray reaches the arrival point N is smaller in the nozzle hole 611B than in the nozzle hole 611C. As a result, the interval between fuel sprays increases between the nozzle holes 611B and 611C. The same applies to the region E14.

  In the region E11, the injection hole 611H located in the forefront along the rotation direction R has a larger reach distance NL than the injection hole 611A. For this reason, the amount transported by the swirl flow until the injected fuel spray reaches the arrival point N is larger in the nozzle hole 611H than in the nozzle hole 611A. As a result, the fuel spray interval is narrowed between the nozzle hole 611H and the nozzle hole 611A. The same applies to the region E13.

  In contrast, in the internal combustion engine 1, the interval NF3 corresponding to the region E12 and the interval NF7 corresponding to the region E14 are set to be narrower than the reference interval NFs. In the internal combustion engine 1, the interval NF1 corresponding to the region E11 and the interval NF5 corresponding to the region E13 are set wider than the reference interval NFs. Therefore, the internal combustion engine 1 sets the intervals NF3 and NF7 to be narrower than the intervals NF1 and NF5, respectively.

  The internal combustion engine 1 can correct the position of the fuel spray transported by the swirl flow to an appropriate position by setting the intervals NF in this way. That is, the internal combustion engine 1 can perform fuel injection in consideration of the influence by setting each interval NF in consideration of the influence of the swirl flow that varies depending on the reach distance NL. As a result, fuel can be appropriately injected into the combustion chamber E.

  In the internal combustion engine 1, the injection holes 611C, 611B, 611B, 611E, 611E, and 611F are formed at the same time with the injection directions of the injection holes 611C, 611D, 611G, and 611H below the reference direction. The injection direction is set to a direction above the reference direction.

  For this reason, the internal combustion engine 1 can also prevent or suppress the fuel spray injected from each of the plurality of nozzle holes 611 from being easily transported to one of the bottom wall surface 311 and the bottom wall surface 712. As a result, the fuel atomization collides with the bottom wall surface 311 and the bottom wall surface 712, thereby preventing or suppressing the fuel atomization. The internal combustion engine 1 can specifically reduce the amount of unburned components and smoke generated by preventing or suppressing the fuel atomization from being inhibited.

  Specifically, the internal combustion engine 1 has a partial shape in the direction along at least one of the bottom wall surface 712 and the bottom wall surface 311 in the direction along the swirl flow in the direction along which each of the arrival points N follows the flow of the swirl flow. Each of the injection angles α can be set so as to be arranged along the partial shapes facing each other in the direction along the central axis P1. Specifically, the internal combustion engine 1 may be configured such that each of the injection angles α is set so that at least one of the distance F1 and the distance F2 is constant between the plurality of injection holes 611.

  That is, the internal combustion engine 1 specifically has, for example, such a configuration, so that it is possible to suitably prevent or suppress the fuel spray from colliding with the bottom wall surface 311 and the bottom wall surface 712. As a result, the fuel atomization can be preferably prevented or suppressed. The internal combustion engine 1 may be configured such that the injection angle α is set so that the distance F1 and the distance F2 are equal for each of the plurality of nozzle holes 611.

  The internal combustion engine 1 may have a configuration in which the interval NF is set as described below. That is, in the internal combustion engine 1, the interval NF4 and the interval NF8 corresponding to the regions between the region E2 and the region E6 are set to be narrower than the reference interval NFs, respectively, and the regions between the region E4 and the region E8 are respectively set. Each of the corresponding intervals NF2 and NF6 may be set wider than the reference interval NFs. Therefore, the internal combustion engine 1 may have a configuration in which the intervals NF4 and NF8 are set narrower than the intervals NF2 and NF6, respectively.

  Even in this case, the internal combustion engine 1 can correct the position of the fuel spray transported by the swirl flow to an appropriate position. The internal combustion engine 1 is configured to set the interval NF1, the interval NF3, the interval NF5, and the interval NF7 as described above, and to set the interval NF2, the interval NF4, the interval NF6, and the interval NF8 in this way. The position of the fuel spray to be transported can be corrected to a more appropriate position.

  The internal combustion engine 1 has a partial shape in a direction along the flow of at least one of the bottom wall surface 712 and the bottom wall surface 311 in the direction along the flow of the swirl flow at each of the reaching points N ′, and the central axis It is also possible to adopt a configuration in which each of the injection angles α is set so as to be arranged along the partial shapes facing each other in the direction along P1. Specifically, the internal combustion engine 1 is a distance in the direction along the central axis P <b> 1, and the distance between the arrival point N ′ and at least one of the bottom wall surface 712 and the bottom wall surface 311 is each of the plurality of nozzle holes 611. It can also be set as the structure by which each injection angle (alpha) is set so that it may become constant between.

  Even in this case, the internal combustion engine 1 can prevent or suppress the fuel spray from colliding with the bottom wall surface 311 or the bottom wall surface 712 by performing fuel injection in consideration of the shapes of the bottom wall surface 712 and the bottom wall surface 311. it can. However, in this case, the fuel spray may easily collide with the bottom wall surface 311 or the bottom wall surface 712 because the swirl flow mode is not taken into consideration. The internal combustion engine 1 injects each of the plurality of nozzle holes 611 such that the distances in the direction along the central axis P1 and the distances between the arrival point N ′ and the bottom wall surface 712 and the bottom wall surface 311 are equal. A configuration in which the angle α is set may be employed.

  In this case, when setting the interval NF, the internal combustion engine 1 may be configured to set the interval NF2, the interval NF4, the interval NF6, and the interval NF8 as described above, for example.

  The internal combustion engine 1 may have a configuration in which the following reference interval NFs ′ is applied instead of the reference interval NFs. FIG. 17 is a diagram illustrating an example of the reference interval NFs ′. The reference interval NFs ′ indicates the nozzle hole interval considering the angular velocity of the swirl flow. The interval NFs1 ′ indicates a reference interval NFs ′ between the nozzle holes 611H and 611A. The interval NFs2 ′ is between the nozzle holes 611A and 611B, the interval NFs3 ′ is between the nozzle holes 611B and 611C, the interval NFs4 ′ is between the nozzle holes 611C and 611D, and the interval NFs5 ′ is the distance between the nozzle holes 611D and 611E. 'Represents the reference interval NFs' between the nozzle holes 611E and 611F, the interval' NFs17 'represents the nozzle holes 611F and 611G, and the interval NFs8' represents the nozzle holes 611G and 611H.

  Here, the region E4 and the region E8 are regions in which the swirl flow circulates upward while swirling, and as a result, the angular velocity of the swirl flow is decelerated by fuel injection. The region E4 and the region E8 are adjacent to a portion of the bottom wall surface 712 where the sign of the gradient that changes in the direction along the flow of the swirl flow is positive.

  The region E2 and the region E6 are regions in which the swirl flow circulates downward while swirling, and as a result, the angular velocity of the swirl flow is accelerated by fuel injection. The region E2 and the region E6 are adjacent to a portion of the bottom wall surface 712 where the sign of the gradient that changes in the direction along the flow of the swirl flow is negative.

  The nozzle holes 611H and 611A are two adjacent nozzle holes among the plurality of nozzle holes 611, and are two nozzle holes for injecting fuel into the region E8 and the region E2. The region E8 and the region E2 constitute a region in which the swirl flow circulates in the direction R in order while swirling, and a region in which the swirl flow circulates downward. On the other hand, the interval NFs1 ′ is set narrower than the reference interval NFs. The same applies to the interval NFs5 ′.

  The nozzle holes 611B and 611C are two adjacent nozzle holes out of the plurality of nozzle holes 611, and are two nozzle holes for injecting fuel into the region E2 and the region E4. The region E2 and the region E4 constitute a region in which the swirl flow circulates in the direction R along the swirl direction and a region in which the swirl flow circulates upward. On the other hand, the interval NFs3 ′ is set wider than the reference interval NFs. The same applies to the interval NFs 7 ′.

  In this way, the internal combustion engine 1 sets the interval NFs1 ′, the interval NFs3 ′, the interval NFs5 ′, and the interval NFs7 ′, thereby correcting the position of the fuel spray transported by the swirl flow accelerated / decelerated by the fuel injection to an appropriate position. it can. Each of the reference intervals NFs ′ takes into account the angular velocity of the swirl flow, for example, the interval NFs1 ′, the interval NFs3 ′, the interval NFs5 ′, and the interval NFs7 ′ are set to the interval NFs1 ′ from the interval NFs1 ′. it can. In this case, the interval NFs ′ is specifically set based on the above-described gradient.

  By using the reference interval NFs ′ instead of the reference interval NFs, the internal combustion engine 1 can set each of the intervals NF in consideration of the influence of the swirl flow and the angular velocity of the swirl flow that vary depending on the reach distance NL. Thereby, the internal combustion engine 1 can obtain higher combustibility.

  The bottom wall surface 712 may have a shape that changes the following cross-sectional area S in a direction along the flow of the swirl flow. FIG. 18 is an explanatory diagram of the cross-sectional area S. FIG. 18 shows the piston 7 as in FIG. FIG. 18 further shows the central portion 31 and the fuel injection valve 6 together. The cross-sectional area S is an area of a portion located on either side along the radial direction from the central axis P4 in the cross section of the combustion chamber E including the central axis P4 in a state where the position of the piston 7 is fixed.

  In this case, the increased portion D2 can be provided so that the cross-sectional area S increases along the direction R. In this case, the reduced portion D1 can be provided so that the cross-sectional area S decreases along the direction R. Therefore, in the internal combustion engine 1, the region E4 and the region E8 corresponding to the increasing portion D2 are regions where the cross-sectional area S increases along the direction R, and the region E2 and the region E6 corresponding to the decreasing portion D1 are the cross-sectional area S. Can be configured to be a region that decreases along the direction R.

  In this case, the angular velocity of the swirl flow changes according to the cross-sectional area S as follows. That is, the angular velocity of the swirl flow changes so that the phase with a relatively small cross-sectional area S is faster than the phase with a relatively large cross-sectional area S. For this reason, in this case, the position of the fuel spray transported by the swirl flow can be corrected to an appropriate position by setting the reference interval NFs ′ in consideration of the angular velocity of the swirl flow that changes in accordance with the cross-sectional area S. In order to set the reference interval NFs ′ in consideration of the angular velocity of the swirl flow that changes according to the cross-sectional area S, the reference interval NFs ′ can be set based on the cross-sectional area S.

  Therefore, the reference interval NFs ′ considering the angular velocity of the swirl flow can be specifically set based on at least one of the gradient and the cross-sectional area S described above. In this case, the internal combustion engine 1 can be configured as follows.

  That is, in this case, when setting the interval NF1, the interval NF3, the interval NF5, and the interval NF7, the internal combustion engine 1 is configured such that each of the interval NF3 and the interval NF7 is set narrower than the corresponding reference interval NFs ′. be able to. At the same time, the internal combustion engine 1 can be configured such that each of the intervals NF1 and NF5 is set wider than the corresponding reference interval NFs ′. The same applies to the case where the interval NF2, the interval NF4, the interval NF6, and the interval NF8 are set.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

Internal combustion engine 1
Cylinder head 3
Central part 31
Bottom wall surface (head bottom wall surface) 311
Fuel injection valve 6
Injection hole 61
Piston 7
Cavity 71
Bottom wall surface (cavity bottom wall surface) 712

Claims (2)

A fuel injection valve for injecting fuel into a combustion chamber in which a swirl flow is generated;
Of the plurality of nozzle holes provided in the fuel injection valve, the nozzle hole interval between two adjacent nozzle holes, and the fuel spray reach distance when the swirl flow is not generated in the combustion chamber is set to be relatively long. A nozzle hole interval between two nozzle holes for injecting fuel into a region to be injected is a nozzle hole interval between two adjacent nozzle holes among the plurality of nozzle holes provided in the fuel injection valve, and a swirl is formed in the combustion chamber. An internal combustion engine that is set to be narrower than a nozzle hole interval between two nozzle holes that inject fuel into a region where a fuel spray reach distance is set to be relatively short when no flow is generated. The internal combustion engine according to claim 1,
A piston provided with a cavity that is exposed to the combustion chamber; and a cylinder head having a central portion that is a portion forming the combustion chamber;
A head bottom having a cavity bottom wall surface having a shape whose height changes in the direction along the flow of the swirl flow, and a central portion whose shape changes in height in the direction along the flow of the swirl flow With walls,
A distance in a direction along the central axis of the combustion chamber, and a fuel spray arrival point that any one of the plurality of nozzle holes injects, and at least one of the cavity bottom wall surface and the head bottom wall surface An internal combustion engine in which an injection direction of each of the plurality of nozzle holes is set so that a distance therebetween is constant between the plurality of nozzle holes.

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