JP5983109B2 - Internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine in which fuel is injected from a cavity recessed at the top of a piston and an injector disposed on a head surface of a cylinder head facing the cavity.

Diesel engines are more efficient than gasoline engines and have less carbon dioxide (CO ₂ ) emissions, which is advantageous from the viewpoint of oil depletion problems and global warming problems. However, the diesel engine is a trade-off in which nitrogen oxides (NOx) and particulate matter (Particulate Matter: hereinafter abbreviated as PM) are discharged, and when one of these NOx and PM decreases, the other increases. This is a problem.

  Therefore, a premixed compression ignition (hereinafter abbreviated as PCI) combustion method that solves the problem of such a diesel engine has attracted attention. This PCI combustion is a combustion method in which the timing of fuel injection into the combustion chamber is made earlier than the compression top dead center of the piston and is ignited after the fuel injection is completed, and substances such as NOx and PM are simultaneously reduced. Can do.

  However, the PCI combustion method has a problem that the applicable operating range is limited to light load. In order to solve the problem, the diameter of the injection hole of the injector (fuel injection valve) is reduced to atomize the fuel. Thus, an attempt has been made to promote evaporation, to quickly generate a uniform and lean premixed gas, and to expand an operation range by PCI combustion (see, for example, Patent Document 1).

  However, when the nozzle hole diameter is made small, it is necessary to inject a required amount of fuel within a certain period in order not to deteriorate the fuel consumption at the full load. Therefore, it is necessary to secure the required total injection hole area, and it is essential to make a plurality of injection holes with a plurality of small diameter injection holes.

  By the way, in a full load in which a large amount of fuel is injected or in an operation region close thereto, in order not to deteriorate fuel consumption, a required amount of fuel corresponding to the load is injected within a certain period (for example, within 30 degrees in crankshaft angle). There is a need. Therefore, when an injector having a small nozzle hole area is used, it is necessary to secure a total nozzle hole area capable of injecting a required amount of fuel at a full load within a certain period, and it is essential to increase the number of injectors. .

  However, when the number of injection holes is increased, the interval between adjacent injection holes becomes narrower, so that the fuel injected from each injection hole 5a of the injector 5 is shown in FIGS. After the spray F collides with the wall surface 11a of the cavity 11, when the spray F spreads in the circumferential direction x (the left-right direction in FIG. 8) of the cavity 11 along the wall surface 11a, the sprays F of adjacent nozzle holes interfere with each other. End up. As a result, a fuel rich region is formed in the portion FL where the sprays F overlap, and the amount of smoke (soot) generated increases.

  The increase in the amount of smoke generated is apparent from the graph shown in FIG. This graph shows a soot production amount for each nozzle hole diameter and number of injection holes 5a of the injector 5, with the vertical axis representing the soot production amount and the horizontal axis representing the fuel injection pressure. According to this graph, it can be seen that the smaller the nozzle hole diameter and the larger the total number of nozzle holes, the greater the amount of soot generated than the larger nozzle hole diameter and the smaller total number of nozzle holes.

To solve this problem, the present inventor is located in a portion where each spray F collides with the wall surface 11a of the cavity 11, as shown in FIG. (A) of FIG. 10B, and a device (see, for example, Patent Document 2) including a combustion chamber 10X formed with a plurality of cavity grooves 15 along the paper surface up-and-down method in FIG. 10B. .

  According to this apparatus, the fuel spray F injected from each injection hole 5 a of the injector 5 collides with the wall surface 11 a of the cavity 11, and then is guided along the cavity groove 15 in the inside / outside direction y of the cavity 11. Therefore, the interference of the adjacent sprays F due to the spray F spreading in the circumferential direction x of the cavity 11 along the wall surface 11a is suppressed. As a result, the formation of a fuel rich region is suppressed, and the amount of smoke generated is reduced.

  On the other hand, as shown in FIGS. 11A to 11D, after the fuel spray F injected from each injection hole 5 a of the injector 5 collides with the wall surface 11 a of the cavity 11, the spray F is applied to the cylinder head 4. When reaching the head surface 12, the spray F develops along the head surface 12 of the cylinder head 4, and there is also a problem that an excessively dense region FL is formed by interfering with the adjacent spray F (not shown). .

JP 2007-2111768 JP 2010-285907 A

  The present invention has been made in view of the above-described problems, and an object of the present invention is to reach the cylinder head after the spray of fuel injected from the injector toward the cavity hits the wall surface of the cavity, and the combustion chamber It is providing the internal combustion engine which can suppress the formation of the over-concentrated region of the fuel due to interference between adjacent sprays.

An internal combustion engine of the present invention for solving the above-mentioned object is provided with a cavity that is recessed at the top of a piston and forms a part of a combustion chamber, a head surface of a cylinder head that faces the cavity, and is disposed on the head surface. And an injector for injecting a plurality of fuel sprays at intervals in a circumferential direction on the wall surface of the cavity, wherein the spray injected from the injector on the head surface is a wall surface of the cavity A plurality of head groove groups that are provided at respective positions that reach after reaching the head , each of the head groove groups has a plurality of head grooves, and Those head grooves in the groove group are adjacent to each other in the circumferential direction of the combustion chamber .

  According to this configuration, even if the fuel spray injected from the injector collides with the wall surface of the cavity and reaches the head surface of the cylinder head facing the cavity, the head groove is provided on the head surface. The fuel spray is promoted to spread along the head groove, that is, along the inside and outside of the combustion chamber. Further, in the direction intersecting the cavity groove, that is, in the circumferential direction of the combustion chamber, the resistance is greatly increased and the spread is relatively suppressed because the mountain portion between the adjacent cavity grooves must be overcome.

  Thereby, interference between adjacent sprays can be suppressed, and formation of a fuel rich region in the combustion chamber can be suppressed, and as a result, generation of smoke can be suppressed.

In addition, if the groove group for heads which consists of a plurality of groove | channels for a head is arrange | positioned for every part to which the spray of the fuel injected from each injection hole of an injector reaches | attains, the spreading of the circumferential direction of a spray can be suppressed more efficiently. it can. Further, the head surface here is a surface including the lower surface of the cylinder head, the lower surface of the intake valve, and the lower surface of the exhaust valve. The head groove group includes the lower surface of the cylinder head, the lower surface of the intake valve, and Regardless of the lower surface of the exhaust valve or the like, it may be provided in a portion where fuel spray reaches.

  In the internal combustion engine, the head groove is formed in the circumferential direction of the combustion chamber when the head groove is formed in parallel to the injection direction of the fuel injected from the fuel injection nozzle toward the cavity. The arrangement is orthogonal to the fuel to be spread, and resistance can be given to the fuel to be spread in the circumferential direction of the combustion chamber.

In addition, in the above internal combustion engine, the cavity wall surface includes a plurality of cavity groove groups provided at positions where the spray collides , and each of the cavity groove groups includes a plurality of cavity groove groups . has a groove cavity, grooves for those cavities in one of the cavity groove group is adjacent in the circumferential direction of the cavity to each other, the groove group for the head and groove group for the cavity face matches When being arranged to, can be the fuel for both the head surface of the cavity wall and the cylinder head can be inhibited from spreading in the circumferential direction of the combustion chamber.

  First, the spray of fuel that collides with the wall surface of the cavity can be promoted to spread along the cavity groove, and can be prevented from spreading in a direction intersecting the cavity groove. Next, even if the spray reaches the head surface of the cylinder head, it can be promoted to spread along the head groove, and can be prevented from spreading in a direction intersecting the head groove.

  In particular, for multi-hole injection of an injector, a head groove group is arranged for each portion where each spray reaches, and a plurality of portions facing each head groove group, that is, a plurality of portions where each spray collides are arranged. It is effective to arrange a cavity groove group composed of the cavity grooves.

  Furthermore, the internal combustion engine has an operation region in which premixed compression ignition combustion is performed in which the fuel injection timing from the injector is set earlier than the compression top dead center of the piston and is ignited after the fuel injection is completed. Then, in order to expand the PCI combustion region by the above effect, the increase in the amount of soot generated due to the interference between the adjacent fuel sprays F generated when the nozzle hole diameter is reduced and the number of nozzle holes is increased is suppressed. Therefore, the combustion area of PCI combustion can be expanded. Thereby, NOx and PM can be reduced simultaneously.

  According to the present invention, the spray of fuel injected from the injector toward the cavity reaches the cylinder head after colliding with the wall surface of the cavity, spreads in the circumferential direction of the combustion chamber, and adjacent sprays interfere with each other. It is possible to suppress the formation of a fuel-rich region due to the above. As a result, the generation of smoke can be suppressed.

  Therefore, since the nozzle hole diameter of the injector can be reduced and the number of nozzle holes can be increased, the combustion region of PCI combustion can be expanded and NOx and PM can be efficiently reduced simultaneously.

It is sectional drawing which shows the combustion chamber of the internal combustion engine of 1st Embodiment which concerns on this invention. It is a top view which shows the head surface of the cylinder head of FIG. It is the figure which showed the movement of the spray of the fuel of the internal combustion engine of FIG. 1, (a) shows sectional drawing of the groove group for heads, (b) shows the top view of the groove group for heads. FIG. 2 is a diagram showing the movement of fuel spray in the internal combustion engine of FIG. 1, immediately after the fuel spray hits the head surface of the cylinder head after colliding with the wall surface of the cavity; (B) is a perspective view of the combustion chamber, and after a certain time has elapsed since the spray of fuel reached the head surface of the cylinder head, (c) a plan view of the cavity and (d) the combustion Shown in perspective view of chamber. It is sectional drawing which shows the combustion chamber of the internal combustion engine of 2nd Embodiment which concerns on this invention. It is a top view which shows the wall surface of the cavity of FIG. FIG. 6 is a diagram showing the movement of fuel spray in the internal combustion engine of FIG. 5, (a) shows immediately after the fuel spray collides with the wall surface of the cavity, and (b) shows the fuel spray on the head surface of the cylinder head. After a certain amount of time has elapsed since the arrival. It is explanatory drawing of the prior art example typically showing a mode that the spray of the fuel injected from the injection hole of the injector of the conventional internal combustion engine collides with a cavity wall surface, and adjacent sprays interfere, (a) is just before a collision. (B) is explanatory drawing just after a collision, (c) is explanatory drawing after progress for a predetermined time after a collision. It is the graph which compared and showed the production amount of soot for every diameter and number of nozzle holes of the injector of the conventional internal combustion engine. It is explanatory drawing which shows a mode that the spray of the conventional internal combustion engine collided with the part of the groove | channel, (a) is sectional drawing of a groove | channel and spray, (b) is the top view which looked at the groove | channel and the spray from the injection direction. is there. FIG. 8 is a diagram showing the movement of fuel spray in a conventional internal combustion engine, and immediately after reaching the head surface of the cylinder head after the fuel spray collides with the cavity wall surface, b) is a perspective view of the combustion chamber, and after a certain time has elapsed since the spray of fuel reached the head surface of the cylinder head, the plan view of the cavity of (c) and the combustion chamber of (d) It shows with a perspective view.

  Hereinafter, an internal combustion engine according to an embodiment of the present invention will be described with reference to the drawings. In addition, although the diesel engine mounted in the motor vehicles like a truck is demonstrated to an example as an internal combustion engine, this invention is not limited to this. In addition, the dimensions and number of the drawings are changed so that the configuration is easy to understand, and the ratios of the thickness, width, length, etc. of each member and each component are not necessarily the ratio or arrangement of what is actually manufactured. This number does not match.

  Here, it supplements about drawing. The circumferential direction of the combustion chamber at the position where the fuel spray collides or reaches is x, and the inside / outside direction of the combustion chamber (or the radial direction of the piston) is y. Moreover, about the dashed-dotted line shown in FIG.1, FIG.2, FIG.5 and FIG. 6, the injection direction Fx of the fuel spray F is shown.

  First, an internal combustion engine according to a first embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the engine (internal combustion engine) 1 includes a well-known engine configuration, and fuel spray F injected from the injector 5 on the head surface 12 of the cylinder head 4 is applied to the wall surface 11 a of the cavity 11. A plurality of head grooves 13 provided along the inner and outer directions y of the combustion chamber 10 are provided, which are located in a portion that reaches after the collision.

  Specifically, the engine 1 includes a cylinder 2, a piston 3, and a cylinder head 4. The cylinder head 4 has an injector (injector) 5, an intake port 6, an intake valve (intake valve) 7, an exhaust port 8, and an exhaust valve. 9 is provided. The combustion chamber 10 is formed in a space surrounded by the inner wall surface of the hollow cylinder 2, the top surface of the piston 3 (including the cavity 11), and the head surface 12 of the cylinder head 4.

  The cavity 11 is a region forming a part of the combustion chamber 10, and the wall surface 11a of the cavity 11 is partitioned by a bottom surface 11b and a side surface 11c that intersects the bottom surface 11b at the outermost periphery of the wall surface 11a. The bottom surface 11b of the cavity 11 is formed so as to gradually become deeper from the center toward the outer periphery, whereby a toroidal combustion chamber 10 is formed. However, the shape of the cavity 11 is not limited to the toroidal type and can be variously changed. For example, other shapes such as a reentrant type and a shallow dish type may be used.

  The tip of the injector 5 is formed in a conical shape, for example, and protrudes into the combustion chamber 10. A plurality of fine nozzle holes 5a are formed at the conical protruding tip of the injector 5, and fuel is simultaneously injected radially from the plurality of fine nozzle holes 5a.

  As described above, in the engine 1 of the present embodiment, the fuel is injected from the fine injection holes 5a and atomized, thereby promoting evaporation and promptly generating a uniform and lean premixed gas. Therefore, it is possible to expand the operation range by premixed compression ignition (hereinafter abbreviated as PCI) combustion, which will be described later.

  Further, by providing a plurality of fine injection holes 5a as much as the required injection hole area can be secured, it is possible to prevent the deterioration of fuel consumption at full load. Here, although not particularly limited, for example, two injection holes 5a are arranged adjacent to each other from the tip of the cone of the injector 5 toward the bottom of the cone. There may be a case where a plurality are arranged along the outer periphery of the cone.

  The diameter and number of the nozzle holes 5a vary depending on the magnitude of the output of the engine 1 and the like. That is, the diameter of each nozzle hole 5a is not particularly limited, but is, for example, 0.1 mm or less. Considering the atomization of fuel and the workability of the nozzle hole 5a, the diameter of the nozzle hole 5a is preferably about 0.08 to 0.05 mm, for example. The total number of nozzle holes 5a is not particularly limited, but is, for example, twenty.

  Such an engine 1 has an operation region by PCI combustion. In this PCI combustion, the fuel injection timing starts earlier than the compression top dead center of the piston 3 and ends earlier than the compression top dead center, and the mixture is ignited after the fuel injection is completed. It is a method. The operation region by PCI combustion is set to a relatively light load region.

  The head surface 12 here is a surface facing the cavity 11 as shown in FIG. 1, and as shown in FIG. 2, the lower surface 12 a of the cylinder head 4, the lower surface 12 b of the intake valve 7, and the exhaust valve 9. It is a surface including the lower surface 12c.

As shown in FIG. 2, the head groove 13 is formed in parallel with the injection direction Fx of the fuel injected from each injection hole 5 a of the injector 5 toward the cavity 11 in the bottom view of the cylinder head 4. A head groove group 14 composed of a plurality of head grooves 13 is formed for each nozzle hole 5a.

Each head groove group 14 is injected from each nozzle hole 5 a of the injector 5 and collides with the wall surface 11 a of the cavity 11, and then sprays the fuel spray F that has reached the head surface 12 of the cylinder head 4 inside and outside the combustion chamber 10. While guiding in the direction y , it functions as the resistance of the fuel that tries to spread in the circumferential direction x of the combustion chamber 10.

  2 shows only the head groove group 14 corresponding to the fuel spray F injected from the six injection holes 5a of the injector 5 in the injection direction Fx indicated by the arrows. Since a plurality of (for example, twenty) fuels are injected from 5 in the circumferential direction of the cavity 11, the plurality of sprays F on the head surface 12 of the cylinder head 4 collide with the wall surface 11 a of the cavity 11. Then, a plurality of head grooves 13, that is, a head groove group 14 is formed in each of the parts that reach after that.

The head groove 13 constituting the head groove group 14 includes the lower surface 12 a of the cylinder head 4, the lower surface 12 b of the intake valve 7, and the lower surface 12 c of the exhaust valve 9, and the head surface 12 of the cylinder head 4 facing the cavity 11. However, as shown in FIG. 2, it may be formed in the same manner except for the vicinity of the center portion of the head surface 12. In short, the head groove 13 may be formed in at least a portion of the head surface 12 where the fuel reaches.

  Further, since the head groove 13 constituting the head groove group 14 is formed on the head surface 12 of the cylinder head 4, the lower surface 12 a of the cylinder head 4 and the lower surface 12 b of the intake valve 7, or the lower surface 12 a of the cylinder head 4. However, there is no problem in guiding the fuel spray F at the boundary between the exhaust valve 9 and the lower surface 12c of the exhaust valve 9.

  A region A where the head groove 13 does not exist is formed between adjacent head groove groups 14. However, the head groove 13 may also be provided in this region A. The head groove 13 provided in the region A is not limited to being parallel to the head groove group 14 as long as the expansion of the fuel in the circumferential direction y of the combustion chamber 10 can be suppressed.

  As shown in FIG. 3A, the cross-sectional shape of each head groove 13 is not particularly limited, but is formed, for example, in a V shape or a U shape.

The depth D of each head groove 13 is not particularly limited. For example, the depth D is set to zero at the center of the head surface 12 and gradually increased from the center to the outer periphery. May be.
Moreover, it may be a substantially constant depth over the entire region, or a portion where the spray F reaches may be deepened from there to other portions along the inside / outside direction of the cylinder 2 and gradually become shallower. Good.

  Further, the depth D may be varied depending on the position in the circumferential direction x of the combustion chamber 10 in one head groove group 14. In short, it is sufficient that the spread of the spray F in the circumferential direction x of the combustion chamber 10 can be suppressed. For example, the depth D is set to about 1 to 5 mm.

  Further, the width W of each head groove 13 is not particularly limited. For example, the width W may be increased toward the end of the head groove group 14. The width W is about 2 to 10 mm.

Such multiple heads grooves 13 along the head face 12 of the cylinder head 4 of the spray F described above, it is sufficient to suppress the spread of the circumferential direction x of the combustion chamber 10, grooves for a plurality of heads 1 3 The way of arrangement is not limited to the above, and can be variously changed. For example, the head grooves 13 may be arranged radially from the center of the head surface 12 of the cylinder head 4 toward the outer periphery.

  Next, the operation of the engine 1 according to the first embodiment of the present invention will be described with reference to FIGS. In the case of the prior art (when the head groove 13 is not formed on the head surface 12 of the cylinder head 4), if the injection holes 5a of the injector 5 are made to be fine and multi-injection holes, the fuel spray F becomes the wall surface 11a of the cavity 11. , It reaches the head surface 12 of the cylinder head 4 and develops in the circumferential direction x of the combustion chamber 10, and interference between adjacent sprays F is likely to occur, and an overconcentrated region is formed in the combustion chamber 10. As a result, there is a problem that the amount of smoke (煤) generated increases.

On the other hand, in the engine 1 of the first embodiment, the fuel spray F injected from the plurality of fine injection holes 5 a of the injector 5 collides with the wall surface 11 a of the cavity 11 and the head of the cylinder head 4. When the surface 12 is reached, as shown in FIGS. 3A and 3B, the resistance is relatively small with respect to the extending direction of the plurality of head grooves 13 (inside / outside direction y of the combustion chamber 10). Therefore, it extends along the extending direction of the head groove 13. On the other hand, relative to the direction intersecting the extending direction of the head groove 13 (the adjacent direction of the plurality of head grooves 13 or the circumferential direction x of the combustion chamber 10) is obstructed by the plurality of head grooves 13. Since the resistance is high, the spread is suppressed.

  That is, the plurality of head grooves 13 urge the spray F to spread along the radiation from the center of the combustion chamber 10, and the spray F is adjacent to the plurality of head groove groups 14 (the circumferential direction of the fuel chamber 10). x) Acts as a guiding part that suppresses spreading (becomes resistance).

  This is because, as shown in FIGS. 4A to 4D, after the spray F of fuel injected from each injection hole 5a of the injector 5 collides with the wall surface 11a of the cavity 11, the spray F is a cylinder. Even when reaching the head surface 12 of the head 4, the spray F does not develop along the head surface 12 of the cylinder head 4, but interferes with an adjacent spray F (not shown) to form an overconcentrated region FL. It will never be done.

  Thus, in the engine 1 of the first embodiment, the plurality of head grooves 13 are formed on the head surface 12 of the cylinder head 4 that arrives after the fuel spray F collides with the wall surface 11 a of the cavity 11 in the combustion chamber 10. Since the fuel spray F is promoted to spread along the head groove 13 and can be prevented from spreading in a direction intersecting with the plurality of head grooves 13, the sprays adjacent to each other can be suppressed. Interference between F and F can be suppressed. Thereby, formation of the fuel rich region in the combustion chamber 10 can be suppressed. As a result, the generation of smoke can be suppressed.

  In addition, when the head groove 13 is formed parallel to the fuel injection direction Fx injected from the injector 5 toward the cavity 11 in the bottom view of the cylinder head 4, the head groove 13 is formed in the combustion chamber 10. The arrangement is orthogonal to the fuel that is going to spread in the circumferential direction x, and the resistance can be given to the fuel that is going to spread in the circumferential direction x of the combustion chamber 10 accurately.

  Next, an internal combustion engine according to a second embodiment of the present invention will be described with reference to FIGS. In addition to the configuration of the first embodiment shown in FIG. 1, the engine 20 is used for a plurality of cavities provided on the wall surface 11a of the cavity 11 along the inside and outside directions of the cavity 11, as shown in FIG. A groove 15 is provided, and the head groove 13 and the cavity groove 15 are arranged to face each other.

  As the cavity groove 15, for example, a well-known groove disclosed in JP 2010-285907 A can be used. Further, as shown in FIG. 6, a cavity groove group 16 composed of the cavity grooves 15 is formed in each of the portions where the spray F collides with the wall surface 11 a of the cavity 11, and is arranged in the same manner as the head groove group 14. A region B where no cavity groove 15 exists is formed between adjacent cavity groove groups 16.

  The head groove group 14 and the cavity groove group 16 are disposed at positions where the combustion chamber 10 overlaps in plan view, and the head groove 13 of the head groove group 14 and the cavity groove 15 of the cavity groove group 16 are the same. Further, the combustion chambers 10 are arranged so as to overlap in plan view, that is, to face each other. Specifically, as shown in FIG. 7A, the convex portion of the head groove group 14 and the convex portion of the cavity groove group 16, and the concave portion of the head groove group 14 and the concave portion of the cavity groove group 16 are provided. Are matched in plan view.

  Next, the operation of the engine 20 will be described with reference to FIG. First, the fuel spray F injected from each nozzle hole 5 a of the injector 5 collides with a cavity groove group 16 provided on the wall surface 11 a of the cavity 11.

  Next, as shown in FIG. 7A, the fuel colliding with the cavity groove group 16 is guided by the cavity groove 15 constituting the cavity groove group 16 and spreads in the inner and outer directions y of the cavity 11, The crest portion between the adjacent cavity grooves 15 functions as a bank (resistance) when fuel about to spread in the circumferential direction x of the cavity 11 gets over, so that the cavity 11 spreads in the circumferential direction x. Is suppressed.

  When the fuel spray F injected from each injection hole 5a of the injector 5 collides with the cavity groove group 16 provided on the wall surface 11a of the cavity 11, the extending direction of the plurality of cavity grooves 15 (in the combustion chamber 10) Since the resistance is small with respect to the inner / outer direction y), it spreads along that direction and, on the other hand, crosses the cavity groove 15 (the direction adjacent to the plurality of cavity grooves 15 or the circumferential direction x of the combustion chamber 10). On the other hand, since it is necessary to get over the crest portion between the adjacent cavity grooves 15, the resistance is relatively large and the spread is suppressed.

  Next, the fuel that has collided with the wall surface 11 a of the cavity 11 rises above the cavity 11 and reaches the head surface 12 of the cylinder head 4.

  Next, as shown in FIG. 7B, the fuel that has reached the head surface 12 is guided by the head groove 13 constituting the head groove group 14 and spreads in the inside / outside direction y of the combustion chamber 10, and next to it. The peak portion between the matching head grooves 13 functions as an embankment (resistance) when fuel about to spread in the circumferential direction x of the combustion chamber 10 gets over, so that the circumferential direction x of the combustion chamber 10 Spreading is suppressed.

  Therefore, even if the fuel spray F injected from each injection hole 5a of the injector 5 collides with the wall surface 11a of the cavity 11 and reaches the head surface 12 of the cylinder head 4, the circumferential direction along the head surface 12 continues. It is possible to suppress the spread to x, suppress the formation of a fuel-rich region due to interference between adjacent sprays F, and reduce the occurrence of smoke.

  In the internal combustion engine of the present invention, the fuel spray F injected from the injector toward the cavity reaches the cylinder head after colliding with the cavity wall surface, spreads in the circumferential direction of the combustion chamber, and adjacent sprays interfere with each other. This suppresses the formation of a fuel rich region. Thereby, even if the nozzle hole diameter of the injector is reduced and the number of nozzle holes is increased, the generation of soot can be reduced, the combustion area of PCI combustion can be expanded, and NOx and PM can be efficiently reduced simultaneously. In particular, it can be used for vehicles such as trucks equipped with diesel engines.

1,20 engine (internal combustion engine)
2 Cylinder 3 Piston 4 Cylinder head 5 Injector 6 Intake port 7 Intake valve 8 Exhaust port 9 Exhaust valve 10 Combustion chamber 11 Cavity 12 Head surface 13 Head groove 14 Head groove group 15 Cavity groove 16 Cavity groove group

Claims (4)

A cavity that is recessed at the top of the piston and forms a part of the combustion chamber, a head surface of the cylinder head that faces the cavity, and a head surface that is disposed on the wall surface of the cavity with an interval in the circumferential direction. An internal combustion engine comprising: an injector for injecting a plurality of fuel sprays;
A plurality of groove groups for the heads provided on each of the portions of the head surface that reach after the spray sprayed from the injector collides with the wall surface of the cavity;
Each of the head groove groups has a plurality of head grooves, and the head grooves in one head groove group are adjacent to each other in the circumferential direction of the combustion chamber. An internal combustion engine. 2. The head groove group, wherein the plurality of head grooves are formed in parallel to an injection direction of fuel injected from the injector toward the cavity. Internal combustion engine. The wall surface of the cavity, comprising a plurality of cavities grooves group provided positioned respective portions where the spray impinges,
Each of these cavity groove groups has a plurality of cavity grooves, and the cavity grooves in one cavity groove group are adjacent to each other in the circumferential direction of the cavity,
The internal combustion engine according to claim 1, wherein the head groove group and the cavity groove group are arranged so as to face each other .   2. An operation region in which premixed compression ignition combustion is performed in which fuel is injected from the injector earlier than the compression top dead center of the piston and ignited after completion of the fuel injection. The internal combustion engine of any one of -3.

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