JP2016217204A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress interference between pieces of injected fuel, to suppress generation of soot or the like.SOLUTION: In a cylinder block 2, formed are a hole 11 through which a piston 12 reciprocatively moves, and a recess 13 communicating with an upper end in the hole 11 and enlarged in an outer peripheral direction with respect to the hole 11. A combustion chamber X is formed by a lower surface 3a of a cylinder head 3, a top surface 12a of the piston 12 and a bottom surface 13a and side surface 13b of the recess 13. Further, an injector 41 is arranged so that a jetting hole 42 faces the combustion chamber X, and fuel is jetted from the jetting hole 42 to the combustion chamber X.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an internal combustion engine that injects fuel into a combustion chamber by an injector.

  There is known an internal combustion engine in which fuel is injected from a injector into a combustion chamber formed by an inner wall surface of a cylinder head and a top surface of a piston to perform combustion. This internal combustion engine is required to suppress the generation of soot, carbon monoxide, and unburned fuel. Generation of soot and the like is promoted by an excess fuel region due to interference between fuels sprayed in a plurality of directions.

  Therefore, there is an internal combustion engine in which a structure for dispersing fuel by collision of sprayed fuel is formed on the top surface of a piston in order to suppress the occurrence of an excessive fuel region (see, for example, Patent Documents 1 to 3). There is also an internal combustion engine in which a plurality of recesses for reducing the flow velocity of the squish gas flowing along the top surface is formed on the top surface of the piston (see, for example, Patent Document 4).

  Further, the main combustion chamber is not formed on the upper surface of the piston, but is formed so as to straddle the inner peripheral side and the outer peripheral side of the cylinder at the upper end of the cylinder. Some internal combustion engines improve the diffusibility of fuel gas by providing a squish area between the piston top surfaces (see, for example, Patent Document 5).

JP 2011-185241 A JP 2011-185242 A JP 2012-92778 A JP 2010-156230 A JP-A-8-128324

  In any of the internal combustion engines of Patent Documents 1 to 4 described above, the combustion chamber is formed by the top surface of the piston at the top dead center and the inner wall surface of the hole. For this reason, the shape of the combustion chamber in the circumferential direction is determined by the shape of the piston and the hole. Therefore, the generation of the excessive fuel region is suppressed by machining the piston top surface. In the internal combustion engine of Document 5, a part of the combustion chamber is provided on the outer peripheral side of the piston, but since a squish area is provided between the lower surface of the cylinder head and the top surface of the piston, the shape of the combustion chamber is flexible. It is difficult to have

  It is an object of the disclosed internal combustion engine to suppress interference between injected fuels by increasing the degree of freedom with respect to the shape of the combustion chamber and to suppress the generation of soot and the like.

  The disclosed internal combustion engine includes a piston, a hole part in which the piston is reciprocated, and a top dead center side end part of the piston in the hole part, and a shape that is enlarged in the outer circumferential direction than the hole part. A combustion chamber formed by the piston and the recess, and an injector for injecting fuel into the combustion chamber through the injection hole.

  According to the disclosed internal combustion engine, interference between injected fuels can be suppressed, and generation of soot and the like can be suppressed.

It is a typical sectional view of an engine. It is a typical partial expanded sectional view of a combustion chamber periphery. It is a typical top view of a combustion chamber. It is a top view which illustrates typically the injection direction of a fuel. It is sectional drawing which illustrates fuel injection typically. It is a typical partial expanded sectional view of the combustion chamber periphery in 2nd Embodiment. It is sectional drawing which illustrates typically the injection of the fuel in 2nd Embodiment. It is a typical top view explaining the shape of the combustion chamber in 3rd Embodiment, and the injection direction of a fuel. It is sectional drawing which illustrates typically the injection of the fuel in 3rd Embodiment. It is a top view which illustrates typically the shape of a combustion chamber and fuel injection in a 4th embodiment. It is sectional drawing which illustrates typically the injection of the fuel in 4th Embodiment.

  Hereinafter, a diesel engine 1 (an example of an internal combustion engine, hereinafter simply referred to as an engine 1) according to an embodiment of the present invention will be described with reference to the accompanying drawings.

  As shown in FIG. 1, the engine 1 includes a cylinder block 2 and a cylinder head 3. The upper half of the cylinder block 2 corresponds to the cylinder portion 10 and is formed with a circular hole 11 extending in the vertical direction. The hole 11 accommodates the piston 12 in a reciprocable state. The lower end of the hole 11 (that is, the end on the bottom dead center side of the piston 12) is connected to the crankcase portion 20. On the other hand, a recess 13 is formed in communication with the upper end of the hole 11 (that is, the end on the top dead center side of the piston 12). The recess 13 forms a combustion chamber X together with the top surface 12 a of the piston 12 and the lower surface 3 a of the cylinder head 3. The recess 13 will be described later together with the combustion chamber X.

  A crankshaft 21 is disposed in the crankcase portion 20 in a rotatable state. A lower end of a connecting rod 23 is attached to a crankpin 22 provided in the crankshaft 21 in a rotatable state. The upper end of the connecting rod 23 is attached to a piston pin 12b included in the piston 12 in a rotatable state. An oil jet 25 that injects oil supplied from the oil passage 24 upward is provided at the upper end of the crankcase portion 20. The oil jetted from the oil jet 25 flows into a cooling channel 12c (see FIG. 2) formed inside the piston 12, and is used for cooling the piston 12. A coolant channel 14 through which a coolant such as cooling water flows is provided around the recess 13 in the cylinder portion 10.

  An intake port 31 and an exhaust port 32 are formed in the cylinder head 3. The intake port 31 is a flow path for introducing fresh air, and the exhaust port 32 is a flow path for discharging exhaust gas. The outlet of the intake port 31 is opened at a position directly above the piston 12 on the lower surface 3 a of the cylinder head 3. The inlet of the exhaust port 32 is opened at a position directly above the piston 12 on the lower surface 3 a of the cylinder head 3, similarly to the outlet of the intake port 31.

  An intake valve 33 is disposed at the intake port 31, and an exhaust valve 34 is disposed at the exhaust port 32. Specifically, the umbrella portion of the intake valve 33 is disposed at the outlet of the intake port 31, and the umbrella portion of the exhaust valve 34 is disposed at the inlet of the exhaust port 32. An upward force is applied to the intake valve 33 and the exhaust valve 34 by valve springs 35 provided on the respective shaft portions. When the rocker arm 38 swings according to the cam profile of the intake cam 36 and the exhaust cam 37, the intake valve 33 and the intake valve 33 move in the vertical direction in accordance with the swing of the rocker arm 38. That is, the intake valve 33 and the intake valve 33 are opened and closed in conjunction with the reciprocating movement of the piston 12 in the vertical direction.

  An injector 41 is disposed between the intake valve 33 and the exhaust valve 34. The injector 41 is a member that injects fuel into the combustion chamber X, and an injection hole 42 is formed at a tip portion disposed in the combustion chamber X. In the present embodiment, five injection holes 42 are formed at equiangular intervals (72-degree intervals) in the circumferential direction. Thus, fuel is injected from the injector 41 in five directions (see FIG. 4). The number of injection holes 42 formed is not limited to five and can be set to any number. For example, seven injection holes 42 may be provided to inject fuel in seven directions, or ten injection holes 42 may be provided to inject fuel in ten directions.

  Next, the combustion chamber X will be described in detail. As shown in FIG. 2, the combustion chamber X of the first embodiment is formed by a recess 13 formed in the cylinder block 2, a piston 12, and a cylinder head 3. The volume of the combustion chamber X is the same as the volume of a general combustion chamber formed at the upper end of the hole 11 without the recess 13. In other words, the combustion chamber X of the first embodiment and the general combustion chamber have the same compression ratio.

  The recess 13 has a shape that is enlarged in the outer peripheral direction (radial direction of the hole 11) than the edge of the hole 11 where the piston 12 reciprocates, and is formed by a bottom surface 13a and a side surface (circumferential surface) 13b.

  The bottom surface 13a is provided in a ring shape with the hole 11 as the center when viewed from the plane direction. In the illustrated example, the bottom surface 13a is formed by an inclined surface that descends from the inner periphery to the outer periphery. In the first embodiment, the top surface 12 a of the piston 12 is formed in a conical shape with a low height, and the bottom surface 13 a of the recess 13 is also an inclined surface having the same inclination angle as the top surface 12 a of the piston 12. Thereby, when the piston 12 is located at the top dead center, the top surface 12a of the piston 12 and the bottom surface 13a of the recess 13 form a series of inclined surfaces (conical surfaces).

  The side surface 13b is configured as an inclined surface that rises from the outer peripheral edge of the bottom surface 13a to the inner peripheral side as the distance from the bottom surface 13a increases. That is, the side surface 13 b is a tapered surface (folded surface) that decreases in diameter as it approaches the cylinder head 3.

  Since the recessed portion 13 that is expanded in the outer peripheral direction from the hole portion 11 is formed, as shown in FIG. 3, the distance L2 from the center of the injector 41 to the outer peripheral edge of the bottom surface 13a is The distance L1 is longer than the distance L1 to the wall surface, and the distance L3 from the center of the injector 41 to the inner periphery of the side surface 13b is also longer than the distance L1. Thereby, as shown in FIG. 4, the distance until the fuel F injected in the five directions collides can be secured, and the fuel F can be sufficiently diffused. In addition, the amount of fuel F that directly collides with the side surface 13b of the recess 13 can be suppressed.

  Further, as shown in FIG. 5, when the piston 12 is located at the top dead center, the bottom surface of the combustion chamber X from the center of the piston 12 in the surface direction to the outer peripheral edge of the recess 13 (the top surface 12 a of the piston 12, The bottom surface 13a) becomes a downward inclined surface. For this reason, the combustion chamber X becomes a space that becomes deeper toward the outer peripheral side. And the injector 41 injects the fuel F toward the center of the height direction in the side surface 13b. Therefore, even if the fuel F injected from the injection hole 42 spreads in the vertical direction, the amount of the fuel F that directly collides with the bottom surface of the combustion chamber X or the ceiling surface of the combustion chamber X (the lower surface 3a of the cylinder head 3) is suppressed. Can do. In addition, since the side surface 13b is a folded surface with respect to the bottom surface 13a, the injected fuel F flows along the side surface 13b and the bottom surface 13a and smoothly changes direction. As a result, it becomes easy to uniformly mix the fuel F and air, and the generation of an excessive fuel region can be suppressed.

  As described above, in the engine 1 of the first embodiment, the cylinder block 2 includes the hole 11 where the piston 12 is reciprocated, and the upper end of the piston 12 in the hole 11 (top dead center side end). A concave portion 13 having a shape that is communicated with the hole portion 11 and that is larger in the outer peripheral direction than the hole portion 11 is formed. A combustion chamber X is formed by the lower surface 3 a of the cylinder head 3, the top surface 12 a of the piston 12, and the bottom surface 13 a and the side surface 13 b of the recess 13. Further, the injector 41 is arranged so that the injection hole 42 faces the combustion chamber X, and the fuel F is injected from the injection hole 42 into the combustion chamber X.

  For this reason, the freedom degree with respect to the shape of the combustion chamber X is raised, the injected fuel F can fully be diffused in the combustion chamber X, and the side surface 13b, the bottom surface 13a, and the ceiling surface (lower surface) of the combustion chamber X The amount of fuel F that directly collides with 3a) can be reduced. As a result, the fuel concentration in the combustion chamber X can be equalized, and the production of soot, carbon monoxide, and unburned fuel can be suppressed. In addition, since the combustion chamber X can be made shallower than the combustion chamber having a general shape and expands in the plane direction, it becomes difficult for the flame to come into contact with the fuel F being diffused, and the fuel F can be burned efficiently. it can.

  Further, regarding the combustion chamber X in the first embodiment, since it is circular when viewed in the planar direction and becomes deeper toward the outer peripheral side, the fuel F injected from the injection holes 42 is directed upward and downward as it goes toward the outer peripheral side. Even if it spreads over, the amount of the fuel F that directly collides with the ceiling surface or the bottom surface 13a can be suppressed, and the concentration of the fuel F injected into the combustion chamber X can be equalized.

  Moreover, since the top surface 12a is made into the cone shape with low height regarding the piston 12, sufficient intensity | strength is securable also under high temperature and a high pressure. In addition, a refrigerant flow path 14 through which the refrigerant flows is provided around the recess 13 in the cylinder block 2. Since the cylinder block 2 is a component having a large volume in the component group constituting the engine 1, a necessary cooling capacity can be easily obtained without impairing the strength of the engine 1.

  Next, the engine 1 which concerns on 2nd Embodiment of this invention is demonstrated. In the engine 1 of 2nd Embodiment, the shape of the side surface 13b in the recessed part 13 is different from the engine 1 of 1st Embodiment. For this reason, below, the part regarding a difference is demonstrated and the description about a common part is abbreviate | omitted.

  As shown in FIG. 6, the combustion chamber X of the second embodiment is also formed by the recess 13 formed in the cylinder block 2, the piston 12, and the cylinder head 3. Also in the second embodiment, the volume of the combustion chamber X is the same as the volume of a general combustion chamber.

  The recess 13 has a shape that is expanded in the outer peripheral direction from the hole 11 in which the piston 12 reciprocates, and is formed by a bottom surface 13a and a side surface 13b.

  The bottom surface 13a has a ring shape centered on the hole 11 when viewed from the plane direction, and is formed by an inclined surface that descends from the inner periphery to the outer periphery. Also in the second embodiment, the top surface 12a of the piston 12 is formed in a conical shape with a low height, and the lower surface 3a of the recess 13 is also an inclined surface having the same inclination angle as the top surface 12a of the piston 12.

  The side surface 13b is configured as an inclined surface that rises from the outer peripheral edge of the bottom surface 13a to the outer peripheral side as the distance from the bottom surface 13a increases. That is, the side surface 13 b is a tapered surface that increases in diameter as it approaches the cylinder head 3.

  Since the concave portion 13 is formed, the distance L5 from the center of the injector 41 to the outer peripheral edge of the side surface 13b is longer than the distance L1 from the injector 41 to the inner wall surface of the hole portion 11 as shown in FIG. . Thereby, the injected fuel F can be sufficiently diffused, and the amount of the fuel F that directly collides with the side surface 13b of the recess 13 can also be suppressed.

  Further, when the piston 12 is located at the top dead center, the combustion chamber X becomes a space that becomes deeper toward the outer peripheral side. Also in the second embodiment, the injector 41 injects the fuel F toward the center in the height direction on the side surface 13b of the recess 13. For this reason, even if the fuel F injected from the injection hole 42 spreads in the vertical direction, the amount of the fuel F that directly collides with the bottom surface of the combustion chamber X or the ceiling surface of the combustion chamber X can be suppressed.

  As described above, in the engine 1 of the second embodiment, the side surface 13b of the recess 13 is a tapered surface that increases in diameter as it approaches the cylinder head 3, so that the distance until the injected fuels collide is ensured. And the fuel F can be sufficiently diffused. In addition, the amount of fuel F that directly collides with the side surface 13b of the recess 13 can be suppressed.

  Next, an engine 1 according to a third embodiment of the present invention will be described. As shown in FIG. 8, in the engine 1 of the third embodiment, the shape of the recess 13A is different from the engine 1 of the first and second embodiments. For this reason, below, the part regarding a difference is demonstrated and the description about a common part is abbreviate | omitted.

  The injector 41 injects the fuel F in a predetermined angular range in the circumferential direction in the combustion chamber X from above the center point of the piston 12 when viewed in the plane direction. In the example shown in FIG. 8, the fuel F is injected in the injection angle range in the five directions indicated by the signs α1 to α5. As described in the first embodiment, the number of fuel injection directions can be arbitrarily set.

  The recessed portion 13A is provided upward from the upper end of the hole portion 11 as in the first and second embodiments. And when the recessed part 13A is seen from a plane direction, the 1st part 15 which belongs to the injection angle range is bulging in the outer peripheral direction rather than the 2nd part 16 which does not belong to the injection angle range. For this reason, the side surface 13b of the concave portion 13 is configured by a first curved side surface 13c that is curved in a convex shape toward the outer circumferential direction and a second curved side surface 13d that is curved in a convex shape toward the inner circumferential direction. ing. That is, by alternately arranging the first curved side surface 13 c and the second curved side surface 13 d, the first portion 15 bulges in the outer peripheral direction from the second portion 16.

  Also in the third embodiment, the volume of the combustion chamber X is the same as the volume of a general combustion chamber, like the combustion chamber X of the first and second embodiments. For this reason, as shown in FIG. 9, about the 1st part 15, the distance L6 from the center of the injector 41 to the outer periphery of the side surface 13b can be ensured, and the injected fuel F can fully be spread | diffused. On the other hand, since the required volume of the second portion 16 can be kept small, the depth of the combustion chamber X (specifically, the top surface 12a of the piston 12 when the piston 12 is located at the top dead center, The distance H1) from the lower surface 3a of the cylinder head 3 can be made wider than the depth of the combustion chamber X in the first and second embodiments. As a result, the lift range of the intake valve 33 and the exhaust valve 34 can be expanded, and the degree of freedom for valve control is increased.

  Next, an engine 1 according to a fourth embodiment of the present invention will be described. In the engine 1 of the fourth embodiment, the arrangement of the injectors 41 is different from the engine 1 of the first to third embodiments. For this reason, below, the part regarding a difference is demonstrated and the description about a common part is abbreviate | omitted.

  As shown in FIGS. 10 and 11, the injector 41 of the fourth embodiment is used sideways, and the tip end portion where the pair of injection holes 42 are formed is arranged on one side portion in the combustion chamber X. . In the examples shown in these drawings, the tip of the injector 41 is disposed on the left side in the figure in the combustion chamber X, and the right side in the figure in the combustion chamber X from each injection hole 42 (other than sandwiching the hole 11). Fuel F is injected along the bottom surface 13a of the recess 13 and the top surface 12a of the piston 12 located at the top dead center.

  The shape of the recess 13 </ b> B forming the combustion chamber X is determined so that the width of the other side in the diameter direction is wider than the width of the one side. As shown in FIG. 10, the widest width W2 in the right half of the hole 11 is the width W1 of the recess 13 at the position of each injection hole 42 provided in the injector 41 (the width W1 in the direction orthogonal to the axial direction of the injector 41). ), The shape of the concave portion 13 in the planar direction (shape of the bottom portion) is determined.

  As shown in FIG. 11, the depth of the recess 13 </ b> B becomes deeper from one side where the tip of the injector 41 is disposed toward the other side across the hole 11. That is, the lower surface 13a of the recess 13B and the top surface 12a of the piston 12 are inclined surfaces that descend from one side toward the other side. Along with this, the side surface 13b of the recess 13 also has a downward distance that increases from one side to the other side.

  The injector 41 injects the fuel F toward the side surface of the other side in the combustion chamber X (the side surface 13b of the recess 13). Since the combustion chamber X has a width in the lateral direction that extends toward the other side portion, the amount of the fuel F that is directly injected into the side surface of the combustion chamber X can be suppressed even if the injected fuel F expands in the lateral direction. Similarly, since the combustion chamber X becomes deeper toward the other side portion, even if the injected fuel F spreads downward, the bottom surface of the combustion chamber X (the lower surface 3a of the recess 13 and the top surface of the piston 12). The amount of direct collision with 12a) can be suppressed. Thereby, it becomes easy to mix the fuel F and air uniformly.

  Accordingly, even in the engine 1 of the fourth embodiment, the injected fuel F can be sufficiently diffused in the combustion chamber X, and the amount of the fuel F that directly collides with the side surface, bottom surface, and ceiling surface of the combustion chamber X. Can be suppressed. As a result, the fuel concentration in the combustion chamber X can be equalized, and the production of soot, carbon monoxide, and unburned fuel can be suppressed.

  The above description of the embodiment is for facilitating the understanding of the present invention, and does not limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes equivalents thereof.

  For example, the technical elements described in one embodiment may be applied to other embodiments. For example, the side surface 13b of the recess 13 in the third embodiment or the fourth embodiment may be folded back as in the first embodiment, or may be expanded upward as in the second embodiment.

  Moreover, in each above-mentioned embodiment, although the engine 1 provided with the cylinder block 2 and the cylinder head 3 was illustrated, it is not limited to the engine 1 of this structure. It is sufficient if the engine includes at least a piston, a hole in which the piston is reciprocated, and a recess communicated with the hole at the upper end of the hole.

DESCRIPTION OF SYMBOLS 1 ... Diesel engine, 2 ... Cylinder block, 3 ... Cylinder head, 3a ... Lower surface of a cylinder head, 10 ... Cylinder part, 11 ... Hole part, 12 ... Piston, 12a ... Top surface of piston, 12b ... Piston pin, 12c ... Cooling channel, 13 ... recess (first and second embodiments), 13A ... recess (third embodiment), 13B ... recess (fourth embodiment), 13a ... bottom surface of recess, 13b ... side surface of recess, 13c ... first 1 curved side, 13d ... 2nd curved side, 14 ... refrigerant flow path, 15 ... 1st part of recessed part (3rd Embodiment), 16 ... 2nd part of recessed part (3rd Embodiment), 20 ... crankcase part , 21 ... crankshaft, 22 ... crankpin, 23 ... connecting rod, 24 ... oil flow path, 25 ... oil jet, 31 ... intake port, 32 ... exhaust port, 33 ... intake valve, 3 ... exhaust valve 35 ... valve spring, 36 ... intake cam, 37 ... exhaust cam, 38 ... rocker arm, 41 ... injector, 42 ... injection holes, X ... combustion chamber, F ... Fuel

Claims (5)

A piston,
A hole portion in which the piston is reciprocally moved, and a cylinder provided with a recess having a shape that is communicated with a top dead center side end portion of the piston in the hole portion and is expanded in an outer peripheral direction from the hole portion;
A combustion chamber formed by the piston and the recess;
An internal combustion engine comprising: an injection hole facing the combustion chamber; and an injector for injecting fuel into the combustion chamber from the injection hole. The injector injects the fuel in the circumferential direction in the combustion chamber from above the piston;
The internal combustion engine according to claim 1, wherein the peripheral surface of the concave portion is an inclined surface that rises from the outer peripheral edge of the bottom surface of the concave portion toward the inner peripheral side as the distance from the bottom surface of the concave portion increases. The injector injects the fuel in the circumferential direction in the combustion chamber from above the piston;
The internal combustion engine according to claim 1, wherein the peripheral surface of the concave portion is an inclined surface that rises from the outer peripheral edge of the bottom surface of the concave portion toward the outer peripheral side as the distance from the bottom surface of the concave portion increases. The injector injects the fuel from above the piston into a predetermined angular range in the circumferential direction in the combustion chamber,
4. The internal combustion engine according to claim 1, wherein the concave portion causes a portion in the predetermined angle range where the fuel is injected to bulge in an outer peripheral direction more than a portion outside the predetermined angle range. 5. The injector causes the fuel to be injected along the top surface of the piston from one side in the combustion chamber to the other side across the hole.
The internal combustion engine according to claim 1, wherein the recess has a shape in which the width of the other side portion in the combustion chamber is wider than the width of the one side portion.

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