JP2014136981A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine for enabling adequate injection of fuel into a combustion chamber by performing fuel injection while considering the flowing behavior of a tumble flow in each of an intake side region and an exhaust side region.SOLUTION: An internal combustion engine 1 includes a fuel injection valve 6 for injecting fuel into a combustion chamber E where tumble flow is produced. The tumble flow produced in the combustion chamber E is a normal tumble flow. An injection angle α8 of an injection hole 611H is set to be smaller than a reference injection angle αs. An injection angle α3 of an injection hole 611C is set to be larger than the reference injection angle αs. The injection hole 611H is an injection hole for injecting the fuel into a region E4 as the intake side region, out of a plurality of injection holes 611. The injection hole 611C is an injection hole for injecting the fuel into a region E2 as the exhaust side region, out of the plurality of injection holes 611.

Description

  The present invention relates to an internal combustion engine.

  An internal combustion engine that performs fuel injection considering the influence of tumble flow is known. Patent Document 1 discloses a fuel direct injection engine in which the fuel injection amount is set so that one of the fuel injection amount on the intake side and the exhaust side of the combustion chamber in which the tumble flow is generated is larger than the other fuel injection amount. Has been.

JP 2010-53710 A

  The combustion chamber has two surfaces including a central axis of the combustion chamber or a straight line extending along the central axis of the combustion chamber, an intake side region divided into the intake side, an exhaust side region divided into the exhaust side, It can be divided into four areas: a front side area divided into the front side and a rear side area divided into the rear side. The front side and the rear side indicate one side and the other side from the straight line included in the two surfaces described above in the direction perpendicular to the central axis of the combustion chamber and the intake / exhaust direction.

  When the tumble flow generated in the combustion chamber is, for example, a normal tumble flow flowing upward in the intake side region, the fuel spray flows upward in the intake side region and downward in the exhaust side region due to the influence of the tumble flow. Will be. When the fuel spray is flowed upward or downward due to the tumble flow, there is a risk that the exhaust emission and the fuel consumption may be deteriorated because the fuel easily adheres to the wall surface of the combustion chamber. For this reason, when generating a tumble flow in the combustion chamber, it is desirable to perform fuel injection in consideration of the flow mode of the tumble flow in each of the intake side region and the exhaust side region.

  An object of the present invention is to provide an internal combustion engine capable of appropriately injecting fuel into a combustion chamber by performing fuel injection in consideration of a flow mode of a tumble flow in each of an intake side region and an exhaust side region. To do.

  The present invention includes a fuel injection valve that injects fuel into a combustion chamber in which a tumble flow is generated, and the combustion chamber includes two central axes of the combustion chamber or a straight line extending along the central axis of the combustion chamber. An intake side region divided into an intake side on the surface, an exhaust side region divided into an exhaust side, a front side region divided into a front side, and a rear side region divided into a rear side, and the fuel The injection hole is one of a plurality of injection holes provided in the injection valve, and fuel is supplied to an area where the tumble flow generated in the combustion chamber flows upward in the intake side area and the exhaust side area. The injection direction of the injection holes to be injected is set to a direction lower than the reference direction, and is any one of the plurality of injection holes provided in the fuel injection valve, the intake side region and the exhaust gas Generated in the combustion chamber in the side region Tumble flow is an internal combustion engine that has been set in the upper direction than the injection direction is the reference direction of the nozzle hole for injecting fuel into a region which flows downward to be.

  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, wherein the cavity has a peripheral portion and a contour of the peripheral portion. A cavity bottom wall surface having a shape whose height changes in a direction along the edge, and a head bottom wall surface having a shape whose height changes in a direction along the outline of the peripheral edge portion of the central portion. A distance in a direction along a central axis of the combustion chamber, and an 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 The injection direction of each of the plurality of nozzle holes can be set so that the distance between the nozzle holes is constant between the plurality of nozzle holes. .

  According to the present invention, fuel can be appropriately injected into the combustion chamber by performing fuel injection in consideration of the flow mode of the tumble flow in each of the intake side region and the exhaust side region.

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 a combustion chamber. It is arrangement | positioning explanatory drawing of a some nozzle hole. It is explanatory drawing of an injection angle. It is explanatory drawing of the propulsion direction of fuel spray. It is the 1st explanatory view of a reaching point. It is the 2nd explanatory view of a reaching point.

  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 a front-rear direction 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 in which a tumble 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 fuel injection valve 6 is provided at the top of the pent roof shape. Therefore, the position along the direction X of the fuel injection valve 6 is set in accordance with the top portion 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 of (here, ten) 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 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 has a raised shape in accordance with the pent roof shape of the central portion 31. The bottom wall surface 712 is provided with an adjacent portion A on each of one side and the other side across the central axis P4 in each cross section of the piston 7 including the central axis P4 (for example, the cross section shown in FIG. 6 or 7). It is provided so as to rise from the height. 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. 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.

  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. In FIG. 8, an increase portion D1, a decrease portion D2, and an intermediate portion D3, which will be described later, are shown together.

  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. A direction R indicates a rotation direction from the phase M1 toward the phase M2 with the central axis P4 as a rotation center.

  The changes in various parameters shown in FIG. 8 are changes in the direction along the contour of the peripheral edge 711. The change in the direction along the contour of the peripheral edge 711 is specifically a change according to the phase around the central axis P4 and the virtual shape C according to the shape of the peripheral edge 711 (see FIG. 9). It means that the change is recognized along the line. Specifically, the virtual shape C is a ring shape 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 outline of the peripheral edge 711. Specifically, the bottom wall surface 712 has a decreasing portion D1, an increasing portion D2, and an intermediate portion D3 as 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 has a constant height H1 in the direction along the contour of the peripheral edge portion 711.

  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 outline of the peripheral edge portion 711 at 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 contour of the peripheral edge 711. On the other hand, the height H1 changes in the same direction as the height H2 in the direction along the contour of the peripheral edge 711. 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 contour of the peripheral edge 711 in a state where the position of the piston 7 is fixed. Because. 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 outline of the peripheral edge portion 711.

  FIG. 10 is an explanatory diagram of the combustion chamber E. FIG. FIG. 11 is an explanatory view of the arrangement of the plurality of nozzle holes 611. In FIG. 11, the nozzle hole 611 is indicated by its central axis. The combustion chamber E has a plurality of regions E1 to E4. Regions E <b> 1 to E <b> 4 exist on the cavity 71.

  The region E1 is a front-side region that is divided into the front side by the surfaces LP1 and LP2 that are two surfaces including the central axis P2. An area E2 is an exhaust side area divided into the exhaust side by the plane LP1 and the plane LP2, an area E3 is a rear side area divided into the rear side by the plane LP1 and the plane LP2, and an area E4 is on the intake side by the plane LP1 and the plane LP2. Each is an intake side area that is divided. The region E1 is a region having a phase range including the phase M1. The region E2 has a phase range including the phase M2, the region E3 has a phase M3, and the region E4 has a phase range including the phase M4.

  Regions E1 to E4 are set according to the arrangement of the fuel injection valve 6. For this reason, the surface LP1 and the surface LP2 are surfaces including the central axis P2. The central axis P2 is a straight line extending along the central axis P1. The surfaces LP1 and LP2 may be surfaces including the central axis P4. When the central portion 31 has a pent roof shape provided in the direction X in accordance with the central axis P1, the surfaces LP1 and LP2 are surfaces including the central axis P1 in relation to the arrangement of the fuel injection valve 6. be able to.

  The region E2 is a region where the tumble flow flows downward. The region E4 is a region where the tumble flow circulates upward. Therefore, a positive tumble flow is generated in the combustion chamber E in the internal combustion engine 1. The region E2 may be a region where the tumble flow circulates upward. At the same time, the region E4 may be a region where the tumble flow flows downward. That is, in the internal combustion engine 1, a reverse tumble flow may be generated in the combustion chamber E.

  The plurality of nozzle holes 611 are provided corresponding to the region E1 to the region E4. The nozzle holes 611J, the nozzle holes 611A, and the nozzle holes 611B indicate the nozzle holes 611 that inject fuel into the region E1. The nozzle hole 611C and the nozzle hole 611D indicate the area E2, the nozzle hole 611E, the nozzle hole 611F, and the nozzle hole 611G indicate the area E3, and the nozzle hole 611H and the nozzle hole 611I indicate the nozzle hole 611 that injects the fuel to the area E4.

  FIG. 12 is an explanatory diagram of the injection angle α. In 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 and the reference reaching point Ns.

  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 α3 indicates the injection hole 611C, 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 611D has an injection angle α4, the injection hole 611E has an injection angle α5, the injection hole 611F has an injection angle α6, The injection hole 611G has an injection angle α7, the injection hole 611I has an injection angle α9, and the injection hole 611J has an injection angle α10 as an injection angle α.

  The reference injection angle αs is an injection angle when a tumble flow is not 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 tumble 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 shape 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.

  As described above, the nozzle hole 611H injects fuel into the region E4. As described above, the region E4 is a region where the tumble flow circulates upward. 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 nozzle hole 611I.

  As described above, the nozzle hole 611C injects fuel into the region E2. As described above, the region E2 is a region where the tumble flow flows downward. On the other hand, the injection angle α3 is set larger than the reference injection angle αs. Therefore, the injection direction of the nozzle hole 611C is set in a direction above the reference direction. The same applies to the nozzle hole 611D.

  When a reverse tumble flow is generated in the combustion chamber E in the internal combustion engine 1, the injection direction of the nozzle holes 611H and 611I can be set to a direction above the reference direction. At the same time, the injection direction of the nozzle holes 611C and 611D can be set to a lower direction than the reference direction.

  FIG. 13A and FIG. 13B are explanatory diagrams of the propelling direction of fuel spray. In FIG. 13A and FIG. 13B, the fuel injected by the nozzle hole 611I is schematically indicated by an arrow. FIG. 13A shows a case where no tumble flow is generated in the combustion chamber E. FIG. FIG. 13B shows a case where a tumble flow is generated in the combustion chamber E.

The angle θ represents an acute angle between the direction Y and the central axis of the fuel injected from the injection hole 611I when viewed along the central axis P2. The angle θ ₀ indicates the angle θ when no tumble flow is generated in the combustion chamber E. The angle θ ₁ indicates the angle θ when a tumble flow is generated in the combustion chamber E.

  When the tumble flow is generated in the combustion chamber E, the propulsion of the fuel spray is inhibited by the tumble flow. At this time, the tumble flow specifically acts so as to inhibit the propulsion of the fuel spray for the component that is vector-decomposed in the direction X when the fuel indicated by the arrow is vector-decomposed in the direction X and the direction Y. On the other hand, the tumble flow does not act on the component that is vector-decomposed in the direction Y so as to inhibit the propulsion of the fuel spray.

For this reason, the angle θ differs between the case where the tumble flow is not generated in the combustion chamber E and the case where the tumble flow is generated in the combustion chamber E. Specifically, the angle θ ₁ is smaller than the angle θ ₀ . Therefore, in the internal combustion engine 1, for example, the fuel spray injected from the injection hole 611 </ b> I is propelled in a phase different from the case where no tumble flow is generated in the combustion chamber E.

  FIG. 14 is a first explanatory diagram of the arrival point N. FIG. In FIG. 14, 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. In FIG. 14, the reaching point N ′ and the injection angle α are shown together.

  The reaching point N is a point at which fuel spray injected from any of the plurality of nozzle holes 611 arrives. Specifically, the reaching point N is a point where fuel spray injected from any of the plurality of nozzle holes 611 arrives when the operating state (for example, the rotational speed and load) of the internal combustion engine 1 is in a predetermined operating state. It has become. The arrival point N3 indicates the injection hole 611C, 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 N3 ′ indicates the injection hole 611C, 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 tumble flow is not generated in the combustion chamber E is actually reached while being influenced by the tumble flow. It has become. Therefore, the reaching point N actually exists in a phase different from the cross section shown in FIG. 14 by the amount affected by the tumble flow. 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.

  FIG. 15 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. 15 also shows the height H1, the height H2, the curve CN, the reaching point N ′, the distance F1, and the distance F2. FIG. 15 shows the change in the direction along the outline of the peripheral edge 711 according to the phase as in FIG.

  The arrival point N1 is at the injection hole 611A, the arrival point N2 is at the injection hole 611B, the arrival point N4 is at the injection hole 611D, the arrival point N5 is at the injection hole 611E, the arrival point N6 is at the injection hole 611F, and the arrival point N7 is at the injection point In the hole 611G, the arrival point N9 indicates the injection hole 611I, and the arrival point N10 indicates the arrival point N corresponding to the injection hole 611J.

  The arrival point N1 ′ is at the injection hole 611A, the arrival point N2 ′ is at the injection hole 611B, the arrival point N4 ′ is at the injection hole 611D, the arrival point N5 ′ is at the injection hole 611E, the arrival point N6 ′ is at the injection hole 611F, The arrival point N7 ′ indicates the injection hole 611G, the arrival point N9 ′ indicates the injection hole 611I, and the arrival point N10 ′ indicates the arrival point N ′ corresponding to the injection hole 611J.

  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, the distance F18 indicates the arrival point N8, the distance F19 indicates the arrival point N9, and the distance F20 indicates the distance F1 corresponding to the arrival point N10.

  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, the distance F28 indicates the arrival point N8, the distance F29 indicates the arrival point N9, and the distance F30 indicates the distance F2 corresponding to the arrival point N10.

  Curves CN indicated by broken lines are positions in the direction along the central axis P1, and are in the direction along the outline of the peripheral edge portion 711 of at least one of the bottom wall surface 712 and the bottom wall surface 311 (here, the bottom wall surface 712). It is a virtual curve which shows each position along a partial shape. Specifically, the partial shape has a ring shape.

  Each of the injection angles α (in other words, the injection direction of each of the plurality of injection holes 611) is a direction along the outline of the peripheral edge 711 of the bottom wall surface 712 in the direction where each of the arrival points N follows the outline of the peripheral edge 711. And are arranged so as to be arranged along the partial shapes 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 contour of at least one of the peripheral wall portions 711 of the bottom wall surface 712 and the bottom wall surface 311 in the direction in which the arrival point N is along the contour of the peripheral wall portion 711. , And can be set so as to be arranged along the partial shapes facing each other in the direction along the central axis 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. In the internal combustion engine 1, the injection angle α8 and the injection angle α9 are set to be smaller than the reference injection angle αs. At the same time, in the internal combustion engine 1, the injection angle α3 and the injection angle α4 are set larger than the reference injection angle αs.

  For this reason, the internal combustion engine 1 is capable of preventing or suppressing the adhesion of fuel to the bottom wall surface 712 and the bottom wall surface 311 by performing fuel injection in consideration of the flow mode of the tumble flow in each of the regions E2 and E4. The fuel can be appropriately injected into the chamber E. Specifically, the internal combustion engine 1 prevents the exhaust emission and the fuel consumption from deteriorating by preventing or suppressing the decrease in the air utilization rate as compared with the case where the tumble flow is not generated in the combustion chamber E. It can be prevented or suppressed.

  The internal combustion engine 1 that performs such fuel injection can share the cylinder head 3 and improve the commonality with the spark ignition internal combustion engine that generates a tumble flow in the combustion chamber. For this reason, the internal combustion engine 1 can also reduce the cost by reducing the manufacturing cost by making the cylinder head 3 common and improving the commonality with the spark ignition internal combustion engine.

  Specifically, the internal combustion engine 1 has a partial shape in the direction along the contour of at least one of the bottom wall surface 712 and the bottom wall surface 311 in the direction in which each of the reaching points N is along the contour of the peripheral wall portion 711. Thus, 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 the fuel spray can be prevented or suppressed from colliding with the bottom wall surface 311 and the bottom wall surface 712. As a result, fuel atomization can be 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 has a partial shape in a direction along the contour of at least one of the peripheral edge portions 711 of the bottom wall surface 712 and the bottom wall surface 311 in the direction in which each of the reaching points N ′ is along the contour of the peripheral edge portion 711. 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 the central axis 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 and the bottom wall surface 712 because the flow mode of the tumble flow 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.

  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 tumble flow is generated;
An intake side region divided into an intake side and an exhaust side region divided into an exhaust side on two surfaces including a central axis of the combustion chamber or a straight line extending along the central axis of the combustion chamber; It has a front side area divided into the front side and a rear side area divided into the rear side,
A nozzle hole of any one of a plurality of nozzle holes provided in the fuel injection valve, wherein the tumble flow generated in the combustion chamber in the intake side region and the exhaust side region flows upward. The injection direction of the injection hole for injecting fuel is set to a direction below the reference direction,
A nozzle hole of any one of a plurality of nozzle holes provided in the fuel injection valve, wherein the tumble flow generated in the combustion chamber of the intake side region and the exhaust side region flows downward. An internal combustion engine in which an injection direction of an injection hole for injecting fuel is set in a direction higher than a reference direction. 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;
The cavity includes a peripheral portion and a cavity bottom wall surface having a shape whose height changes in a direction along the contour of the peripheral portion, and the center portion has a height in a direction along the contour of the peripheral portion. It has a head bottom wall with a changing shape,
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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