JP2005273552A - Spark ignition type direct injection engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spark ignition type direct injection engine capable of improving uniformity of air fuel mixture and performing uniform combustion with excellent properties. <P>SOLUTION: This spark ignition type direct injection engine is provided with a combustion chamber 10, an ignition plug 32, an intake valve 20, an exhaust valve 22, an injector 36 and a fuel injection control means. A piston has a cavity 9 formed on a crown face and opened upwardly, and the injector 36 has upper nozzle holes directed to an electrode part and a plurality of lower nozzle holes directed to an opening edge of the cavity 9 of the piston. An angle between the axial center of the upper nozzle hole and the axial center of the lower nozzle hole adjacent to the upper nozzle hole is set larger than the sum of half of a spray angle of fuel injection from the upper nozzle hole in a compression stroke and half of a spray angle of fuel injection from the lower nozzle hole adjacent to the upper nozzle hole in the compression stroke. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a spark ignition direct injection engine, and particularly to a spark ignition direct injection engine including an injector having a plurality of injection holes.

  There is known a spark ignition type direct injection engine provided with an injector for directly injecting fuel into a combustion chamber. This type of engine is configured to improve fuel efficiency by performing fuel injection during the compression stroke and by causing the air-fuel mixture to be unevenly distributed in the vicinity of the spark plug and performing stratified combustion. The present invention has been developed based on such a technique.

  In the direct injection engine as described above, under a predetermined condition such as at the time of full load, fuel is injected during the intake stroke, and the air-fuel mixture is uniformly distributed in the cylinder and burned uniformly. However, in a direct injection engine, since the mixture is unevenly distributed in the vicinity of the spark plug and is suitable for stratified combustion, when the uniform combustion is performed by fuel injection in the intake stroke, the mixture is The required torque cannot be obtained due to poor vaporization or unevenness, and problems such as smoke, particulates, and HC may occur at full load.

The inventors of the present invention promote the vaporization / mixing of the injected fuel in the direct injection engine by devising the direction of the axis of the injector nozzle (center axis of fuel injection) and the injection timing from the injector. It was found that the homogeneity of the air-fuel mixture in the combustion chamber can be improved even in a region where the engine load is high.
The present invention has been made based on such knowledge, and an object thereof is to provide a spark ignition type direct injection engine capable of improving the homogeneity of the air-fuel mixture and performing uniform combustion with excellent characteristics. To do.

  According to the present invention, a combustion chamber constituted by a cylinder, a cylinder head, and a piston, an ignition plug having an electrode portion disposed at the upper center of the combustion chamber, and an intake air disposed at a ceiling portion of the combustion chamber. A valve, an exhaust valve disposed at a position facing the intake valve across the ignition plug, an injector disposed adjacent to the intake valve and injecting fuel into the combustion chamber, and fuel injection from the injector A spark ignition type direct injection engine having a fuel injection control means for controlling the piston, wherein the piston is provided with a cavity formed on a crown surface and opening upward, and the injector is directed to the electrode portion. An upper nozzle hole and a plurality of lower nozzle holes directed toward the opening edge of the cavity of the piston, the axis of the upper nozzle hole and the axis of the lower nozzle adjacent to the upper nozzle hole The angle is a half angle of the injection angle of the fuel injection from the upper nozzle in the compression stroke and a half angle of the injection angle of the fuel injection from the lower nozzle adjacent to the upper nozzle in the compression stroke There is provided a spark ignition direct injection engine characterized by being set at an angle larger than the sum of the above.

According to such a configuration, the fuel injected from the upper nozzle and the fuel injected from the lower nozzle do not interfere with each other and attract each other, so that the fuel injected from the upper nozzle is the electrode of the spark plug. In the vicinity of the portion, the fuel injected from the lower nozzle is reliably blown to the opening edge of the cavity formed on the piston crown surface.
Furthermore, since the fuel sprayed from the lower nozzle to the opening edge of the cavity is dispersed by hitting the peripheral edge, mixing with air is promoted, and homogenization of the air-fuel mixture is promoted. On the other hand, the fuel blown from the upper nozzle to the vicinity of the electrode portion allows the air-fuel mixture to be unevenly distributed in the vicinity of the electrode portion, so that stable combustion can be achieved even if so-called heavy EGR in which exhaust of 20% or more of the intake air is introduced is performed. Can be secured.

According to another preferred aspect of the present invention, the axis of the lower nozzle hole is arranged so as to be directed to the opening edge of the cavity of the piston located at an intermediate height position of the cylinder.
According to such a configuration, when fuel injection is performed in the middle of the intake stroke when the piston reaches the middle height position of the cylinder, the fuel injected from the lower injection hole collides with the opening edge of the cavity on the piston crown surface and diffuses. To do. In the middle of the intake stroke, since the flow velocity of the intake air flow is high, the fuel that has diffused by colliding with the opening edge of the cavity is placed on the intake air flow having a high flow velocity and is dispersed in the combustion chamber. Accordingly, in such a configuration, homogenization of the air-fuel mixture is promoted when injection is performed in the middle of the intake stroke.

According to another preferred aspect of the present invention, the opening of the cavity has an oval shape whose major axis extends from the exhaust valve side toward the intake valve side.
According to another preferred aspect of the present invention, the opening edge of the cavity has an arcuate cross section.
According to such a configuration, since the fuel collides with the opening edge having an arc-shaped (R-shaped) cross section and is dispersed in a wide range, the homogenization of the air-fuel mixture is further promoted.

According to another preferred aspect of the present invention, the upper nozzle hole is composed of one or two nozzle holes directed to the left and right or below the electrode portion, and the lower nozzle hole is composed of four or more nozzle holes.
According to such a configuration, the fuel from the upper nozzle is unevenly distributed in the vicinity of the electrode portion, and the fuel from the lower nozzle is uniformly dispersed in the combustion chamber. Since the number of upper nozzle holes directed to the electrode part is smaller than the number of lower nozzle holes directed to the cavity of the piston crown surface, the fuel mixture is unevenly distributed in the vicinity of the electrode part, but the air-fuel mixture exists in a homogeneous state in the combustion chamber. A stratified state can be formed. For this reason, stable combustion can be ensured even if so-called heavy EGR in which exhaust of 20% or more of the intake air is introduced is performed.

According to another preferred aspect of the present invention, the upper nozzle hole is composed of three nozzle holes directed to the left and right and below the electrode portion, and the lower nozzle hole is composed of three or more nozzle holes.
According to such a configuration, the fuel from the upper nozzle is unevenly distributed in the vicinity of the electrode portion, and the fuel from the lower nozzle is uniformly dispersed in the combustion chamber. Since there is no or little difference between the number of upper nozzle holes directed to the electrode part and the number of lower nozzle holes directed to the cavity of the piston crown surface, the degree of uneven fuel distribution in the vicinity of the electrode part is increased and stratification is promoted. . Further, since the nozzle hole directed toward the cavity edge of the piston crown surface is also provided, homogenization of the air-fuel mixture in the combustion chamber is ensured.

  ADVANTAGE OF THE INVENTION According to this invention, the spark-ignition type direct injection engine which can improve the homogeneity of air-fuel | gaseous mixture and can perform the uniform combustion of the outstanding characteristic is provided.

Hereinafter, a configuration of a spark ignition direct injection engine according to a preferred embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of a spark ignition direct injection engine 1 according to an embodiment of the present invention, and FIG. 2 is an enlarged sectional view of the vicinity of the combustion chamber of the engine.
The engine 1 includes a cylinder block 4 in which four cylinders 2 (only one is shown in FIG. 1) arranged in series are formed, and a cylinder head 6 arranged on the cylinder block 4. . A piston 8 is disposed in the cylinder 2 so as to be able to reciprocate in the vertical direction.

  3 is a plan view showing a crown surface (top surface) of the piston 8, and FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. As shown in FIGS. 3 and 4, a concave cavity 9 that opens upward is formed on the crown surface of the piston 8. As shown in FIG. 3, the cavity 9 has a semi-rugby ball shape having an oval opening at the upper end. Further, as shown in FIG. 4, the cavity 9 has an opening edge 9a having an arcuate cross section (R shape).

A combustion chamber 10 is formed between the piston 8 and the cylinder head 6. As shown in FIG. 2, the combustion chamber 10 is a so-called pent roof type combustion chamber having two inclined surfaces extending from a substantially central portion of the ceiling portion of the cylinder 2 to the vicinity of the lower end surface of the cylinder head 6.
On the other hand, a crankshaft 12 is rotatably supported below the piston 8 in the cylinder block 4, and the crankshaft 12 and the piston 8 are connected via a connecting rod 14.

  As shown in FIG. 1 and FIG. 2, the cylinder head 6 has two intake ports 16 and two exhaust ports 18 in parallel (only one of them is shown in FIGS. 1 and 2). It is formed with. Each of the two intake ports 16 is opened on one inclined surface of the combustion chamber, and an intake valve 20 that is opened and closed at a predetermined timing is seated on each intake port 16. Each intake valve 20 has a generally circular shape and includes a valve umbrella portion 20a that opens and closes the intake port 16, and a rod-shaped stem 20b that extends from the center of the valve umbrella portion 20a. The two exhaust ports 18 are opened alongside the other inclined surface of the combustion chamber, and an exhaust valve 22 that opens and closes at a predetermined timing is seated on these exhaust ports 18.

  The cavity 9 in the crown surface of the piston 8 is exhausted from the side of the intake valve 20 with the longitudinal axis A of the oval opening passing between the adjacent intake valves 20, 20 and between the exhaust valves 22, 22. It arrange | positions so that it may extend to the valve 22 side.

  As shown in FIG. 1, an intake passage 24 that communicates with the intake port 16 of each cylinder 2 is connected to one side of the engine 1. The intake passage 24 is for supplying the intake air filtered by an air cleaner (not shown) to the combustion chamber 6 of the engine 1, and the intake sucked into the engine 1 sequentially from the upstream side to the downstream side. A hot wire air flow sensor 26 for detecting the amount of air, an electric throttle valve 28 for restricting the intake passage 24, and a surge tank 30 are arranged. The electric throttle valve 28 is not mechanically connected to an accelerator pedal (not shown) and is driven by an electric drive motor (not shown).

  Further, the intake passage 24 is branched into independent passages connected to the cylinders 2 on the downstream side of the surge tank 30, and the downstream end portion of the independent passages is further branched into two to provide two intake air for each cylinder. Each port 16 is connected.

  A spark plug 32 is disposed at the center of the upper portion of the combustion chamber 10 at substantially the center of the four intake / exhaust valves 20, 20, 22, 22. An electrode 32 a at the tip of the spark plug 32 is located at a position protruding a predetermined distance from the ceiling of the combustion chamber 10, and an ignition circuit 34 is connected to the base end of the spark plug 32. The ignition plug 32 is energized at a predetermined timing.

  An injector 36 is attached between the intake valves 20 at the peripheral edge of each combustion chamber 10. The injector 36 is a so-called multi-hole injector in which a plurality of injection holes are formed at the tip, and is disposed so as to face the exhaust valve 22 with the electrode portion 32a of the spark plug 32 interposed therebetween. Each injector 36 is connected to a fuel distribution pipe 38. The fuel distribution pipe 38 supplies high-pressure fuel supplied from the fuel supply system 40 to each injector 36.

  As shown in FIG. 1, an exhaust passage 42 that exhausts exhaust gas from the combustion chamber 10 is connected to the other side of the engine 1. The upstream end of the exhaust passage 42 is an exhaust manifold 44 that is branched and connected to the exhaust port 18 of each cylinder 2. A linear O2 sensor 46 for detecting the oxygen concentration in the exhaust gas is disposed at the collection portion of the exhaust manifold 44. The linear O2 sensor 46 detects the air-fuel ratio based on the oxygen concentration in the exhaust.

  Further, the upstream end of the exhaust pipe 48 is connected to the collecting portion of the exhaust manifold 44. A three-way catalyst 50 and a NOx absorption catalyst 52 are attached to the exhaust pipe 48 in order from the upstream side to the downstream side. The NOx absorption catalyst 52 adsorbs NOx when the oxygen concentration in the exhaust gas is high, releases NOx adsorbed as the oxygen concentration decreases, and reduces the released NOx by HC, CO, etc. in the exhaust gas. It is an adsorption reduction type catalyst.

  The exhaust pipe 48 is connected to an upstream end of an EGR passage 54 that recirculates a part of the exhaust gas to the intake system. The downstream end of the EGR passage 54 is connected to the intake passage 24 between the throttle valve 28 and the surge tank 30. The EGR passage 54 is provided with an EGR valve 56 whose opening degree can be adjusted electrically.

  As shown in FIG. 1, the engine 1 includes an ECU (engine control unit) 58. The ECU 58 receives output signals from various sensors such as a crank angle sensor 60 that detects the rotation angle (engine speed) of the crankshaft 12, the airflow sensor 26, the linear O2 sensor 46, and the accelerator opening sensor 62, Based on the input output signal, operations of the ignition circuit 34, the injector 36, the electric throttle valve 28, the EGR valve 58, and the like are controlled.

Fig.5 (a) shows the control map used by the fuel-injection control performed in the engine 1 of this embodiment. As shown in FIG. 5 (a), in the engine of the present embodiment, split injection control in which fuel is injected separately into an intake stroke and a compression stroke, and fuel is injected once in an intake stroke, under the control of the ECU 58. The batch injection control to be performed is performed by switching.
That is, in the engine of the present embodiment, split injection is performed from a low load in the engine low rotation region, a high load in the middle rotation region, a medium load in the high rotation region, and a batch injection in the other regions. Yes. In general, in a direct-injection gasoline engine, the air-fuel mixture is easily homogenized in the middle rotation region. Therefore, in the present embodiment, the split injection is performed only in the high load region in the middle rotation region. In the middle rotation region, a configuration in which divided injection is not performed even in a high load region may be employed.

  Also, as shown in Fig. 5 (b), the control characteristics are set so that the load for starting batch injection or split injection becomes high in the high rotation range for an engine aimed at homogenization in the high rotation range. May be. In the case of such an engine, the homogeneity deteriorates in the collective injection as the rotational speed becomes lower. Therefore, the load for starting the divided injection is set lower as the rotational speed becomes lower.

  Further, in an engine aiming at homogenization in a low rotation range, as shown in FIG. 5C, control characteristics for performing split injection on the high load side in the entire rotation range may be set.

  In the divided injection of the present embodiment, as shown in the time chart of FIG. 6, fuel injection is performed three times in total, once in the intake stroke and twice in the compression stroke. The injection in the intake stroke is preferably performed in the middle of the intake stroke where the flow velocity of the intake flow is high. Specifically, the injection timing in the intake stroke is such that the injection starts at 0 ° to 100 ° after top dead center (ATDC) and completes at 100 ° to 200 ° after top dead center (ATDC). It is preferable to set the injection timing in the stroke, and it is more preferable to set so that the injection timing exists in the range of 60 ° to 120 ° after top dead center (ATDC).

  The first injection in the compression stroke is, for example, before the compression top dead center (BTDC) 30 ° to 140 after the middle of the compression stroke, which is the time when the cylinder pressure becomes high and the movement of the injected fuel is suppressed. It is preferably performed at the time of °.

  Further, the second injection in the compression stroke is, for example, before the compression top dead center (BTDC) 0 ° to 90 ° after the middle of the compression stroke, which is a time when the piston approaches the top dead center and the injected fuel is pushed up. It is preferred to be done at the time.

The injection amount Q1 of the fuel injection in the intake stroke, the injection amount Q2 of the first fuel injection in the compression stroke, and the injection amount Q3 of the second fuel injection in the compression stroke are: Q1> Q2 ≧ Q3 It is set to satisfy the relationship.
Further, the fuel injection amount is set so that the relationship of Q2> Q3 is satisfied in the high load region and the relationship of Q2 ≧ Q3 is satisfied in the other regions.

  Next, the arrangement of a plurality of nozzle holes formed at the tip of the injector 36 will be described. FIG. 7 is a view showing the arrangement of a plurality of nozzle holes at the tip of the injector 36. As shown in FIG. 7, the injection hole 64 of the injector 36 according to the present embodiment includes two injection holes (upper injection holes) 64 a and 64 b arranged above, and four injection holes (lower injection holes) arranged below. 64c, 64d, 64e, 64f. In this embodiment, each nozzle hole has the same diameter (about 0.15 mm), and the spread (injection angle) of the fuel injected from each nozzle hole is also the same.

  FIG. 8 schematically shows a three-dimensional inclination angle between the axis L of the injector 36 and the axes 66a, 66b, 66c, 66d, 66e, 66f of the nozzle holes 64a, 64b, 64c, 64d, 64e, 64f. It is a figure. As shown in FIG. 8, the axial centers 66a and 66b of the upper injection holes 64a and 64b, that is, the fuel injection direction (center axis of the injected fuel) are respectively left and right of the electrode part 32a of the spark plug 32. It is arranged to be oriented to the area.

The lower nozzle holes 64c, 64d, 64e, and 64f are provided on the crown surface of the piston when the shaft centers 66c, 66d, 66e, and 66f are located at intermediate positions in the height direction of the cylinder 2 (cylinder). It is arranged to be oriented.
More specifically, the lower nozzle holes 64c, 64d, 64e, and 64f have regions in the vicinity of the opening edge 9a of the cavity 9 in the crown surface of the piston 8 in which the axial centers 66c, 66d, 66e, and 66f are located at intermediate positions (in FIG. Are arranged so as to be oriented. Accordingly, the fuel injected from the lower nozzle holes 64c, 64d, 64e, and 64f when the piston 8 is at the intermediate position collides with a region in the vicinity of the opening edge 9a indicated by a dotted line in FIG.

  FIG. 9 is a drawing showing the relationship between the angles between the axes of adjacent nozzle holes and the injection angles from these nozzle holes. As shown in FIG. 9, in the injector 36 of the present embodiment, the axial center 66a (or 66b) of the upper nozzle 64a (or 64b) and the lower nozzle 64c (or 64b) adjacent to the upper nozzle 64a (or 64b). 64d) and the angle 66 formed by the axis 66c (or 66d) is a half angle of the injection angle α of the fuel injection from the upper nozzle 64a (or 64b) in the compression stroke and the upper nozzle 64a in the compression stroke. (Or 64b) is set to an angle larger than the sum of the injection angle β of the fuel injection from the lower injection port 64c (or 64d) adjacent to (or 64b).

Here, the definition of the injection angle α (β) described above will be described with reference to FIG. The injection angle α (β) refers to the opening angle of the geometric fuel injection area from the injector 36. The geometric fuel injection area is a droplet area of fuel spray when there is no intake flow in the combustion chamber 10.
Hereinafter, specific examples will be described. As shown in FIG. 10, at a position 20 mm downstream from the injection hole A point of the injector 36, two points B and C where the imaginary plane through which the spray center line passes and the contour of the fuel spray intersect are determined, and the injection angle is expressed by ∠BAC Let α (β) (α = ∠BAC).

As an actual measurement method of the injection angle α (β), for example, a laser sheet method is used. That is, first, a sample of a dry sol belt corresponding to the fuel property is used as the fluid ejected by the injector 36, and the pressure of this sample is a predetermined value (for example, 12 MPa) within the range of the fuel pressure actually used at room temperature. Set to. Moreover, as an atmospheric pressure, the pressure vessel provided with the laser passage window which can image | photograph spraying, and the window for a measurement is pressurized to 0.5 Mpa, for example. Then, a drive pulse signal having a predetermined pulse width is input to the injector 36 to inject fuel so that the fuel injection amount per pulse becomes 9 mm ³ / stroke at room temperature. At this time, a laser sheet light having a thickness of 5 mm is irradiated to the fuel spray so as to pass through the spray center line, and a spray image is taken with a high-speed camera from a direction orthogonal to the laser sheet light surface. Take a picture. Then, the injection angle α (β) is determined according to the above definition based on the imaging screen 1.56 milliseconds after the input timing of the above drive pulse signal.
Note that the spray contour in the photographed image is the contour of the droplet-shaped sample particle area, and since the sample particle area is brightened by the laser sheet light, the spray is sprayed from the portion where the brightness changes in the photographed image. I try to figure out the outline.

  In the present embodiment, the injection angle of each of the nozzle holes 64a, 64b, 64c, 64d, 64e and 64f is 20 °, and the axis 66a (or 66b) of the upper nozzle hole 64a (or 64b) and the upper nozzle hole 64a (or 64b). The angle Θ formed by the axis 66c (or 66d) of the lower nozzle 64c (or 64d) adjacent to the lower nozzle hole 64c is set to 65 °.

  With such an arrangement, there is no mutual interference between the fuel (sprays) injected from the upper nozzle hole 64a (or 64b) and the lower nozzle hole 64c (or 64d) adjacent to the upper nozzle hole 64a (or 64b).

  Further, the opening angle Φ between the axial centers 66c and 66e (66d and 66f) of the lower nozzle holes 64c and 64e (64d and 64f) adjacent to each other is set slightly larger than the injection angle 20 ° from each nozzle hole. As a result, the fuel injected from the lower nozzle holes 64c and 64e (or 64d and 64f) adjacent to each other in the vertical direction has a relatively small opening angle Φ, and the mutual interference is suppressed while preventing the fuel from coming off from the crown surface of the piston 8. As a state in which no generation occurs, the air will fly in the direction of the piston 8 in a state where there is no attracting contact between the sprays.

  Further, the axial lines 66c, 66d, 66e, 66f of the lower nozzle holes 64c, 64d, 64e, 64f directed to the crown surface of the piston 8 are directed to the opening edge 9a of the cavity 9 having an arc shape (R shape). Therefore, when the piston 8 is in the intermediate position, the fuel F injected from the lower injection holes 64c, 64d, 64e, 64f collides with the arcuate opening edge 9a, as schematically shown in FIG. Diffuse towards the surroundings. For this reason, the homogeneity of the air-fuel mixture is improved.

  Next, an engine according to a second embodiment of the present invention will be described. The engine of the second embodiment is different from the engine of the first embodiment in that a third upper nozzle hole is provided and three lower nozzle holes are provided. Hereinafter, these differences will be described.

  FIG. 12 is a view similar to FIG. 7 showing the arrangement of the nozzle holes in the engine of the second embodiment. As apparent from FIG. 12, in the second embodiment, a third upper nozzle hole 68c is provided at a position below the upper nozzle holes 68a, 68b. The third upper nozzle hole 68c is arranged such that its axis 70c is directed below the electrode portion 32a of the spark plug 32.

  Furthermore, in the engine of the second embodiment, three lower nozzle holes 68d, 68e, 68f are provided. The axial centers 70d, 70e, and 70f of the lower nozzle holes 68d, 68e, and 68f are also formed on the opening edge 9a of the cavity 9 formed on the crown surface when the piston 8 is in the intermediate position, as in the first embodiment. It is arranged to be oriented. Specifically, they are arranged so as to be directed to regions arranged at substantially equal intervals on the opening edge 9a indicated by a dotted line in FIG.

  In the engine of the second embodiment having such a configuration, the fuel mixture injected from the third upper injection hole 68c is unevenly distributed below the electrode portion 32a, and the fuel injected from the other upper injection holes 68a and 68b. The air-fuel mixture is unevenly distributed to the side of the electrode portion 32a. As a result, in the engine of the present embodiment, the degree of uneven distribution of the air-fuel mixture in the vicinity of the electrode portion 32a is higher than in the engine of the first embodiment. That is, a stronger stratification state is formed than in the engine of the first embodiment.

The present invention is not limited to the above-described embodiments, and various changes or modifications can be made within the scope of the technical matters described in the claims.
In the first embodiment, the axial center of the upper nozzle hole is directed to the left and right of the electrode, but the structure may be directed only to the left or right of the electrode or only downward.

It is drawing which shows schematic structure of the spark ignition direct injection engine of preferable embodiment of this invention. It is sectional drawing to which the combustion chamber vicinity of the engine of FIG. 1 was expanded. It is a top view which shows the relationship of the collision of the spray with the piston crown surface of the engine of FIG. FIG. 4 is a sectional view taken along line IV-IV in FIG. 3. 2 is a control map of fuel injection control performed in the engine of FIG. 1. It is a time chart of the fuel injection at the time of the division | segmentation injection in the engine of FIG. It is drawing which shows arrangement | positioning of the nozzle hole in the engine of FIG. It is the figure which showed typically the three-dimensional inclination | tilt angle of the axial center of an injector, and the axial center of each nozzle hole. It is a schematic drawing which shows the relationship between the angle between the axial centers of an adjacent nozzle hole, and the injection angle from each nozzle hole. It is explanatory drawing explaining the definition of the injection angle which concerns on embodiment of this invention. It is drawing which shows typically the path | route of the fuel injected from the upper nozzle. It is drawing which shows arrangement | positioning of the nozzle hole in the engine of 2nd Embodiment. It is a top view which shows the collision relationship of the piston crown surface and spray in the engine of FIG.

Explanation of symbols

1: Engine 2: Cylinder 10: Combustion chamber 20: Intake valve 22: Exhaust valve 32: Spark plug 36: Injector 64: Injection port 64a, 64b: Upper injection port 64c, 64d, 64e, 64f: Lower injection port 66a, 66b, 66c, 66d, 66e, 66f: axial center of the nozzle

Claims (6)

A combustion chamber constituted by a cylinder, a cylinder head, and a piston; an ignition plug having an electrode portion disposed at an upper center of the combustion chamber; an intake valve disposed at a ceiling portion of the combustion chamber; and the ignition plug An exhaust valve disposed at a position opposed to the intake valve across the fuel cell, an injector disposed adjacent to the intake valve and injecting fuel into the combustion chamber, and fuel injection control for controlling fuel injection from the injector A spark ignition direct injection engine comprising:
The piston has a cavity formed on the crown surface and opening upward;
The injector includes an upper nozzle directed to the electrode portion, and a plurality of lower nozzles directed to an opening edge of the cavity of the piston,
The angle formed by the axis of the upper nozzle and the axis of the lower nozzle adjacent to the upper nozzle is a half of the injection angle of fuel injection from the upper nozzle in the compression stroke, and the angle in the compression stroke. An angle larger than the sum of the angle of the fuel injection from the lower nozzle adjacent to the upper nozzle and one-half of the injection angle;
This is a spark ignition direct injection engine. The axial center of the lower nozzle is arranged to face the opening edge of the cavity of the piston located at the middle height position of the cylinder,
The spark ignition direct injection engine according to claim 1. The opening of the cavity has an oval with a long axis extending from the exhaust valve side toward the intake valve side,
The spark ignition direct injection engine according to claim 1 or 2. The opening edge of the cavity is an arc-shaped cross section,
The spark ignition direct injection engine according to any one of claims 1 to 3. The upper nozzle hole is composed of one or two nozzle holes directed to the left and right or below the electrode part,
The lower nozzle hole consists of four or more nozzle holes,
The spark ignition direct injection engine according to any one of claims 1 to 4. The upper nozzle hole consists of three nozzle holes directed to the left and right and below the electrode part,
The lower nozzle hole consists of three or more nozzle holes,
The spark ignition direct injection engine according to any one of claims 1 to 4.

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