JP2001164940A - In-cylinder fuel injection spark ignition internal combustion engine - Google Patents

Abstract

(57) [Problem] To provide in-cylinder fuel injection capable of obtaining stable combustion by significantly suppressing the occurrence of misfires and torque fluctuations without significantly changing the structure of an internal combustion engine body. To provide a spark ignition internal combustion engine. SOLUTION: A top surface of a piston is provided with a cavity 15 having a substantially cylindrical peripheral wall surface and a bottom wall surface smoothly connected to the peripheral wall surface. The fuel injected from the fuel injection valve 13 toward the bottom wall surface of the cavity 15 forms an air-fuel mixture that rises from the bottom wall surface of the cavity 15 to the spark plug 6 along the peripheral wall surface. The ignition plug 6 is positioned and attached to the cylinder head 7 so that two ignition gaps 6c, 6c are arranged in the direction in which the intake valve 3 is arranged (vertical direction in FIG. 2). The distance between the two ignition gaps 6c, 6c is set so as to ignite a combustible mixture of the mixture M rising toward the ignition plug 6, and is set to 20 mm or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-cylinder fuel injection type internal combustion engine in which fuel is directly injected into a cylinder and burned by spark ignition.

[0002]

2. Description of the Related Art An in-cylinder fuel injection type spark ignition internal combustion engine of this type is disclosed, for example, in JP-A-9-158736. This Japanese Patent Laid-Open No. 9-1
The in-cylinder fuel injection spark ignition internal combustion engine disclosed in Japanese Patent No. 58736 discloses a piston having a cavity formed in a concave portion having a peripheral wall surface on the top surface and a bottom wall surface smoothly connected to the peripheral wall surface. An ignition plug disposed above the cavity, and a fuel injection valve for injecting fuel toward the cavity, and the fuel injected from the fuel injection valve toward the cavity, along the cavity. An air-fuel mixture rising toward the spark plug is formed, and the air-fuel mixture is ignited by the spark plug and burned.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide an in-cylinder fuel injection type spark ignition internal combustion engine as described above, which is capable of preventing the occurrence of misfire and torque fluctuation without a significant structural change of the internal combustion engine body. An object of the present invention is to provide an in-cylinder fuel injection type spark ignition internal combustion engine capable of obtaining a stable combustion by greatly suppressing the combustion.

[0004]

As a result of the investigation and research by the present inventors, the following facts have been newly found. In the above-described in-cylinder fuel injection type spark ignition internal combustion engine, an ignition plug having one ignition gap is usually used, and as shown in FIG. Time during which an appropriate combustible mixture exists (for example, the A / F is about 5 to 25 when there is no EGR, and the above-mentioned A / F range becomes narrower with an increase in the EGR amount when there is EGR). (Range of the crank angle) is extremely limited. FIG. 14 shows a temporal change of the mixture concentration around the ignition plug (ignition cap). The mixture concentration around the ignition plug (ignition cap) at the time of ignition is within the range of the appropriate combustible mixture concentration (region A in the figure) on average on average within the extremely limited time described above, and is stable. Even when driving is performed,
Depending on the cycle, the mixture concentration suddenly exceeds the proper combustible mixture concentration range due to various factors, and the mixture concentration is excessively rich (point B in the figure) or too thin (point in the figure). , Point C), and it was found that there was a possibility of misfiring. The occurrence of such a misfire causes deterioration of HC (hydrocarbon) emission, deterioration of drivability, and the like.

Further, in the above-described in-cylinder fuel injection type spark ignition internal combustion engine, as shown in FIG. 15, the peripheral region of the air-fuel mixture away from the ignition plug (ignition cap portion) 201 has a low air-fuel mixture concentration. Fuel injection valve 20
This tendency becomes more remarkable as the time lapse from the injection of the fuel by No. 2 becomes longer. FIG. 15 shows the change over time in the concentration of the mixture and the flame in the cylinder. In the figure, the regions indicated by D to H show the region where the mixture is present, and the region D is the rich mixture. Is present, and the concentration of the air-fuel mixture decreases as the area E, the area F, and the area G become smaller.
The region H is a region where a lean mixture exists. A region I in the drawing indicates a region in which a flame generated by the ignition of the air-fuel mixture exists, and a region J in the drawing indicates an unburned region. The above-described lean mixture in the peripheral region (region H) cannot be completely burned, and a part of the region J is discharged as unburned fuel, which causes deterioration of HC emission. Furthermore, since the amount of unburned fuel fluctuates in each cycle, the combustion efficiency in each cycle and, consequently, the generated torque in each cycle fluctuates. It turned out to be. In FIG. 15, reference numeral 203 denotes a cavity formed on the piston top surface.

[0006] Based on the above research results, the in-cylinder fuel injection type spark ignition internal combustion engine according to the present invention has:
A cavity comprising a recess having a peripheral wall surface and a bottom wall surface smoothly connected to the peripheral wall surface is formed, an ignition plug disposed above the cavity, a fuel injection valve for injecting fuel toward the cavity, The fuel injected from the fuel injection valve forms a mixture that rises toward the spark plug, and the spark plug can ignite a combustible mixture of the mixture that rises toward the spark plug. And a plurality of ignition gaps provided at a predetermined distance from each other. Here, in the present invention,
This also includes the shape, structure, and the like in which the peripheral wall and the bottom wall of the cavity have the same curvature and have the same curved surface.

In the in-cylinder fuel injection type spark ignition internal combustion engine according to the present invention, fuel injected toward the cavity from the fuel injection valve forms an air-fuel mixture rising toward the spark plug along the cavity, and ignition is performed. Since the plug has a plurality of ignition gaps provided at a predetermined distance so as to ignite a combustible air-fuel mixture of the air-fuel mixture rising toward the ignition plug, all of the plurality of ignition gaps are provided. On the other hand, the probability that the mixture concentration around each ignition gap part simultaneously exceeds the range of the appropriate combustible mixture concentration is extremely small,
Even if a misfire occurs in any of the ignition gaps,
The ignition is normally performed in the other ignition gap portions, and normal combustion is performed for the cylinder. For this reason, the occurrence of misfire is largely suppressed.

Further, if the ignition is performed at a plurality of spatially separated ignition gaps, the combustion speed in each of the ignition gaps is the same, but the combustion is accelerated in the entire cylinder. . For this reason, it is possible to burn the injected fuel before it excessively diffuses to the surroundings, and it is possible to greatly suppress the occurrence of torque fluctuation. Further, fuel efficiency can be improved due to a synergistic effect of an increase in combustion efficiency and an increase in the equal capacity of the cycle.

Further, with a simple configuration in which the spark plug has a plurality of ignition gaps, the occurrence of misfire and torque fluctuations is greatly suppressed, and a significant structural change of the internal combustion engine body is involved. Never.

Preferably, the predetermined distance is not more than 20 mm. As described above, by setting the predetermined distance to 20 mm or less, a plurality of ignition gap portions can be arranged at a position where the combustible air-fuel mixture exists, and the effect of greatly reducing the occurrence of misfire and torque fluctuation can be obtained. Can be obtained reliably.

Further, the in-cylinder fuel injection type spark ignition internal combustion engine has a plurality of cylinders and the same number of ignition coils as the number of cylinders. It is preferable that the cylinders having the phase difference of a predetermined crank angle are set as a set, and the cylinders are connected so as to simultaneously ignite one ignition gap of each of the cylinders forming the set. With such a configuration, it is possible to suppress an increase in the number of ignition coils due to a plurality of ignition gap portions. Occurrence can be prevented.

[0012] Preferably, the predetermined crank angle is 360 °. As described above, a pair of cylinders having a phase difference of 360 ° in crank angle is formed as one set, and one ignition coil is connected so as to simultaneously ignite one ignition gap portion of each cylinder in the set. In this case, one of the cylinders forming a pair is in the exhaust-intake stroke, and a useless spark is generated in the ignition gap of this cylinder. However, the cylinder internal pressure is low and the energy required for dielectric breakdown is low. Therefore, the energy of the ignition coil is injected into the ignition gap of the other cylinder to which the compression pressure is applied, and the ignition coil surely applies the energy for ignition to the ignition gap of the combustion cylinder. can do. In addition, the charging time to the ignition coil can be ensured to be the longest for each of the cylinders forming a set.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a cylinder fuel injection type spark ignition internal combustion engine according to the present invention will be described below in detail with reference to the drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description.

FIG. 1 is a longitudinal sectional view showing an in-cylinder fuel injection type spark ignition internal combustion engine according to the present invention, FIG. 2 is a plan view of a lower surface of a cylinder head, and FIG. 3 is a side view of an ignition plug. is there. The in-cylinder fuel injection type spark ignition internal combustion engine 1 includes a cylinder head 7 having an intake port 2, an intake valve 3, an exhaust port 4, an exhaust valve 5, and a spark plug 6, a cylinder block 9 in which a cylinder 8 is formed, and a cylinder. 8 (cylinder block 9) reciprocally movable piston 1
0. The combustion chamber 11 includes a space defined by a lower surface of the cylinder head 7, a top surface 10a of the piston 10, and a peripheral wall surface 15a and a bottom wall surface 15b of the cavity 15. A plurality of piston rings 12 are provided on the side surface of the piston 10 to prevent gas from flowing from the combustion chamber 11.

The fuel injection valve 13 is attached to the cylinder head 7 on the side of the intake valve 3 so that the tip 13a of the nozzle is inclined toward the center axis of the cylinder 8. In this embodiment, there are two intake valves, and the fuel injection valve 13 is located between the intake valves 3. The fuel injected from the fuel injection valve 13 is formed such that the fuel injected from the fuel injection valve 13 flattens the spray flow in a plane including the central axis of the cylinder 8 and forms a fan-shaped flow in a plane substantially perpendicular to the central axis of the cylinder 8. So that the spray center does not hit the spark plug 6 directly.
Squirts slightly downward. The injection direction varies from engine to engine, but generally ranges from 20 ° to 70 ° below the cylinder.

On the top surface 10a of the piston 10, a cavity 15 having the nozzle tip 13a of the fuel injection valve 13 and the ignition plug 6 at both ends is formed in a state opened to the combustion chamber 11. The cavity 15 has a substantially cylindrical peripheral wall surface 15a and a bottom wall surface 15b smoothly connected to the peripheral wall surface 15a. At the compression top dead center, the ignition gaps 6c, 6c of the ignition plug 6 And the center of the bottom wall surface 15b of the cavity 15 or a position slightly closer to the cylinder head 7 side from the center. Here, the fuel injection valve 13 is mounted so as to be inclined so that the nozzle tip 13a is directed substantially toward the cylinder center axis.
Will be injected toward the bottom wall surface 15b. The width of the cavity 15 (peripheral wall surface 15 a) in the direction in which the intake valve 3 (exhaust valve 5) is disposed (the vertical direction in FIG. 2) is such that the spray tip of the fuel injected from the fuel injection valve 13 is When it reaches the center, it is larger than the width of the spray projected on a plane perpendicular to the central axis of the cylinder 8. That is,
At this time, the spray in the space inside the combustion chamber 11 is
Rises into the cavity 15. Further, of the wall surface of the cavity 15 (the connection portion between the peripheral wall surface 15a and the bottom wall surface 15b), at least the spark plug 6 side has a concave curvature with respect to the cavity 15.

In the compression stroke from the bottom dead center position where the piston 10 completes the intake to the top dead center, the air in the combustion chamber 11 is compressed. When the fuel is injected from the fuel injection valve 13 in the compression process, the spray particles of the injected fuel are mixed with the central axis of the cylinder 8 and the nozzle tip 13 a of the fuel injection valve 13.
When projected onto a plane including the following, the light is scattered flat, when projected onto a plane perpendicular to the central axis of the cylinder 8, in a fan shape, and substantially symmetrically with respect to the spark plug 6. After the fuel exits the injection hole, it rapidly spreads and evaporates while rapidly mixing with the surrounding high-temperature air. Therefore, the spray particles collide with the inner wall of the cylinder 8 at high speed, and a large amount of liquid spray is applied to the bottom wall 15b of the cavity 15. Never get wet. The spray is formed from the bottom wall surface 15b of the cavity 15 along the connection portion between the peripheral wall surface 15a and the bottom wall surface 15b, and further from the connection portion between the peripheral wall surface 15a and the bottom wall surface 15b along the peripheral wall surface 15a to above the cavity 15. A flow of the mixture M rising toward the spark plug 6 is formed. This and piston 1
With the rise of 0, the air-fuel mixture M is distributed around the ignition plug 6 before the compression top dead center.

As shown in FIGS. 2 and 3, the ignition plug 6 has two outer electrodes (ground electrodes) 6a, 6a and 2
And a pair of outer electrode 6a and center electrode 6b constitute an ignition gap portion 6c, and a pair of outer electrode 6a and center electrode 6c respectively.
b is connected to another ignition coil (not shown). The spark plug 6 is connected to the intake valve 3 as shown in FIG.
It is positioned and attached to the cylinder head 7 so that the two ignition gaps 6c, 6c are arranged in the direction in which the (exhaust valve 5) is arranged (vertical direction in FIG. 2).

The distance between the two ignition gaps 6c, 6c is set such that a combustible mixture of the mixture M rising toward the ignition plug 6 (ignition gaps 6c, 6c) can be ignited. , As shown in FIG.
The following is preferred. FIG. 4 was obtained from a number of experiments and the like.
FIG. 7 is a diagram showing a relationship between a distance between ignition gap portions 6c and a width of a fuel injection timing at which stable operation is possible. As shown in FIG. 4, when the distance between the two ignition gaps 6c, 6c is larger than 20 mm, the width of the fuel injection timing at which the in-cylinder fuel injection type spark ignition internal combustion engine 1 can operate stably is As a result, the operation of the in-cylinder fuel injection spark ignition internal combustion engine 1 becomes unstable. The lower limit of the distance between the ignition gaps 6c is preferably about 2 to 3 mm, but may be about 1 mm.

At a predetermined ignition timing, the ignition plug 6 (ignition gap portions 6c, 6c)
The mixture M existing around the (ignition gaps 6c, 6c) is ignited. Spark plug 6 (ignition gap portions 6c, 6c)
The flame formed by igniting c) spreads in the cavity 15 by flame propagation. At this time, the squish flow between the cavity 15 and the top surface 10a of the piston 10 causes the air-fuel mixture to stay in the cavity 15 and to be prevented from scattering outside the combustion chamber, so that the ignition plug 6 (the ignition gap 6c,
The flame formed according to 6c) develops in the cavity 15. Therefore, there is no fear of misfiring or extinguishing.

FIGS. 5 and 6 show a case where an ignition plug having one ignition gap is used, obtained from a number of experiments and the like performed using the in-cylinder fuel injection type spark ignition internal combustion engine 1 described above. 5 shows a comparison result with a case where an ignition plug 6 having two ignition gaps 6c, 6c is used.

FIG. 5 is a diagram showing the relationship between the injection timing and the torque fluctuation value. In FIG. 5, a circle indicates the characteristic when ignition is caused by one ignition gap, and a black circle indicates a 2 The figure shows the characteristics when ignition is caused by the two ignition gaps 6c. As shown in FIG. 5, when the ignition is performed by the two ignition gaps 6c and 6c, the torque fluctuation can be reduced and the torque fluctuation is smaller than when the ignition is performed by the single ignition gap. The control range of the injection timing becomes wide, and the combustion chamber 11
It can be seen that stable combustion is being performed inside.

FIG. 6 is a diagram showing a stable operation region in the relationship between the injection timing and the ignition timing. The region O shows the stable operation region when ignition is caused by one ignition gap, and the region P Are two ignition gap portions 6c, 6
c shows a stable operation region in the case of ignition. As shown in FIG. 6, the size of the region P is significantly larger than that of the region O, and the two ignition gaps 6c, 6c are larger than the case where ignition is performed by one ignition gap.
In the case of ignition, the region in which the in-cylinder fuel injection type spark ignition internal combustion engine 1 can operate stably (the control range of the injection timing and the ignition timing) is wider. It can be seen that stable combustion is performed.

The middle point Q in FIG. 6 indicates a point (injection timing and ignition timing) at which the optimum operation can be performed with respect to fuel consumption and torque fluctuation. When ignition is caused by one ignition gap, While operation at this point Q was not possible, operation at point Q becomes possible if the ignition is performed by the two ignition gaps 6c, 6c.

As described above, according to the present embodiment, the fuel injected from the fuel injection valve 13 toward the bottom wall surface 15b of the cavity 15 allows the bottom wall surface 15b
, An air-fuel mixture M rising toward the spark plug 6 along the peripheral wall surface 15a is formed.
And two ignition gaps 6c, 6c provided at a predetermined distance from each other so as to ignite the combustible mixture of the mixture M rising toward 6C, the probability that the concentration of the mixture M existing around each of the two ignition gaps 6c, 6c simultaneously exceeds the appropriate combustible mixture concentration range is extremely small.
Even if a misfire occurs in any one of the ignition gaps 6c, the other ignition gaps 6c are normally ignited, and normal combustion is performed for the cylinder. For this reason, the occurrence of misfire is largely suppressed.

If the ignition is performed at two spatially separated ignition gaps 6c, 6c, each ignition gap 6c
Although the combustion speeds at c and 6c are the same, the combustion is accelerated when viewed over the entire cylinder. For this reason, it is possible to burn the injected fuel before it excessively diffuses to the surroundings, and it is possible to greatly suppress the occurrence of torque fluctuation. Also,
The fuel efficiency can be improved by the synergistic effect of increasing the combustion efficiency and increasing the equal capacity of the cycle.

In order to provide a plurality of ignition gaps,
A configuration in which a plurality of spark plugs are provided for one combustion chamber is also conceivable. However, not only the structural change of the cylinder head 7 but also a layout problem such as securing a space for providing a plurality of spark plugs, Alternatively, a manufacturing problem such as an increase in the number of processing steps for plug holes for mounting a plurality of spark plugs occurs. However, in the above-described in-cylinder fuel injection type spark ignition internal combustion engine 1, the occurrence of misfires and torque fluctuations is greatly suppressed by a simple configuration in which the ignition plug 6 has two ignition gaps 6c, 6c. As a result, the structure of the internal combustion engine body (such as the cylinder head 7) is not significantly changed, and the above-described problem does not occur.

The distance between the two ignition gaps 6c, 6c is preferably not more than 20 mm. Thus, the distance between the two ignition gaps 6c, 6c is 20 mm.
By doing so, the two ignition gaps 6c, 6c can be reliably arranged at the position where the combustible mixture exists in the mixture M, and as shown in FIG. The effect that generation is greatly suppressed can be reliably obtained.

Next, a modification of the in-cylinder fuel injection type spark ignition internal combustion engine according to the present invention will be described with reference to FIG. FIG.
FIG. 9 is a plan view of a lower surface of a cylinder head in a modified example. In the above-described embodiment, as shown in FIG. 2, the ignition plug 6 has two ignition gap portions 6c, 6c in the direction in which the intake valve 3 (exhaust valve 5) is disposed (vertical direction in FIG. 2). As it is disposed, it is positioned and attached to the cylinder head 7, so that combustion in the direction in which the intake valve 3 (exhaust valve 5) is disposed (vertical direction in FIG. 2) is accelerated.
Therefore, when unburned fuel is likely to remain at the end of the cavity 15 in the direction in which the intake valve 3 (exhaust valve 5) is disposed (vertical direction in FIG. 2), the two ignition gaps 6c, 6c are connected to the intake valve 3 By disposing the exhaust valve 5 in the disposition direction (vertical direction in FIG. 2), combustion in the cavity 15 in the disposition direction of the intake valve 3 (exhaust valve 5) (vertical direction in FIG. 2) is prevented. It is possible to prevent the unburned fuel from being left at the above-mentioned end portions due to acceleration. Therefore, when the unburned fuel component is likely to remain at the end of the cavity 15 in the direction orthogonal to the direction in which the intake valve 3 (exhaust valve 5) is disposed (the left-right direction in FIG. 2), it is shown in FIG. Thus, the two ignition gaps 6
By arranging c and 6c in a direction perpendicular to the arrangement direction of the intake valve 3 (exhaust valve 5) (the left-right direction in FIG. 7), it is possible to suppress the unburned fuel from remaining at the above-mentioned ends. Can be.

In this embodiment, the ignition plug 6
However, the number of the ignition gaps 6c is not limited to three, and may be three or more. For example, FIG. As in the modification shown in FIG. 7B, four ignition gaps 6c, 6c, 6c, 6c may be provided. FIG. 8 shows a modification of the spark plug,
(A) is a plan view and (b) is a side view.

As a further modification, as shown in FIGS. 9A and 9B, the outer electrode 6a and the center electrode 6
b, an outer electrode 6a and a center electrode 6b are provided with an intermediate electrode 6d insulated from the center electrode 6b.
One ignition gap 6c may be formed. 9A and 9B show a modification in which the intermediate electrode 6d is provided, wherein FIG. 9A is a plan view and FIG. 9B is a side view. With such a configuration, a spark can be simultaneously blown by the two ignition gaps 6c, 6c with one ignition coil.

Next, the in-cylinder fuel injection type spark ignition internal combustion engine 1
The connection between the ignition plug and the ignition coil of each cylinder when is a multi-cylinder will be described with reference to FIGS.

FIG. 10 is a schematic diagram for explaining the connection between the ignition plug and the ignition coil when the in-cylinder fuel injection type spark ignition internal combustion engine 1 has two cylinders. The mutual phase difference between the two cylinders is, for example, 36 degrees in crank angle.
0 °. Each of the spark plugs 21 and 22 disposed in each cylinder is connected to two outer electrodes (ground electrodes) 6a and 6a and two center electrodes 6b and 6b, similarly to the spark plug 6 of the above-described embodiment. The outer electrode 6a and the center electrode 6b, which form a pair, constitute an ignition gap 6c. The outer electrodes 6a, 6a of the respective spark plugs 21, 22 are in a state of being electrically connected.

Two ignition coils 31, the same number as the number of cylinders,
32 each have two high voltage terminals. One high-voltage terminal of the ignition coil 31 is connected to one center electrode 6 b of the ignition plug 21, and the other high-voltage terminal of the ignition coil 31 is connected to one center electrode 6 of the ignition plug 22.
b. One high-voltage terminal of the ignition coil 32 is connected to the other center electrode 6b of the ignition plug 21, and the other high-voltage terminal of the ignition coil 32 is connected to the other center electrode 6b of the ignition plug 22. I have.

FIG. 11 is a schematic diagram for explaining the connection between the ignition plug and the ignition coil when the in-cylinder fuel injection type spark ignition internal combustion engine has four cylinders. The in-cylinder fuel injection type spark ignition internal combustion engine 40 has four cylinders 40a, 40b, 4
0c, 40d, and the respective cylinders 40a, 40b, 4
The phase difference between 0c and 40d is 180 ° in crank angle.
It has been. The ignition sequence of the in-cylinder fuel injection type spark ignition internal combustion engine 40 is in the order of the cylinder 40a, the cylinder 40c, the cylinder 40d, and the cylinder 40b, and the mutual phase difference between the cylinder 40a and the cylinder 40d is 360 in crank angle. °, and the phase difference between the cylinders 40b and 40c is 360 ° in crank angle.

Each spark plug 4 disposed in each cylinder
1, 42, 43, and 44 are, like the spark plug 6 of the above-described embodiment, two outside electrodes (ground electrodes) not shown.
And two center electrodes 6b, 6b. The outer electrode and the center electrode 6b forming a pair each constitute an ignition gap.

Four ignition coils 51, the same number as the number of cylinders,
Each of 52, 53, and 54 has two high-voltage terminals. One high-voltage terminal of the ignition coil 51 is connected to one center electrode 6b of the ignition plug 41 of the cylinder 40a, and the other high-voltage terminal of the ignition coil 51 is connected to the cylinder 4a.
0d is connected to one center electrode 6b of the ignition plug 44. One high-voltage terminal of the ignition coil 52 is connected to the cylinder 40.
The ignition plug 52 is connected to one center electrode 6b of the ignition plug 42, and the other high-voltage terminal of the ignition coil 52 is connected to one center electrode 6b of the ignition plug 43 of the cylinder 40c. One high-voltage terminal of the ignition coil 53 is connected to the cylinder 4
0b is connected to the other center electrode 6b of the ignition plug 42, and the other high voltage terminal of the ignition coil 53 is connected to the other center electrode 6b of the ignition plug 43 of the cylinder 40c. One high voltage terminal of the ignition coil 54 is connected to the other center electrode 6b of the ignition plug 41 of the cylinder 40a, and the other high voltage terminal of the ignition coil 54 is
It is connected to the other center electrode 6b of the ignition plug 44 of the cylinder 40d.

FIG. 12 is a schematic diagram for explaining the connection between the ignition plug and the ignition coil when the in-cylinder fuel injection type spark ignition internal combustion engine is a V-type six cylinder. The in-cylinder fuel injection type spark ignition internal combustion engine 60 has six cylinders 60a, 60
b, 60c, 60d, 60e, and 60f, and each of the cylinders 60a, 60b, 60c, 60d, 60e, and 60f.
The mutual phase difference is 120 ° in crank angle. The ignition order of the in-cylinder fuel injection type spark ignition internal combustion engine 60 is as follows: cylinder 60a, cylinder 60e, cylinder 60c, cylinder 60
f, the cylinder 60b, and the cylinder 60d in this order. For example, the mutual phase difference between the cylinder 60a and the cylinder 60b is
0a to cylinder 60b, crank angle 480 °
In addition, in the case of going from the cylinder 60a to the cylinder 60b, the crank angle becomes 240 °.

Each of the spark plugs 6 arranged in each cylinder
Each of 1, 62, 63, 64, 65, and 66 has two outer electrodes (ground electrodes) (not shown) and two center electrodes 6b and 6b, similarly to the spark plug 6 of the above-described embodiment. The pair of outer electrode and center electrode 6b constitute an ignition gap.

Six ignition coils 71, the same number as the number of cylinders,
Each of 72, 73, 74, 75, and 76 has two high-voltage terminals. One high voltage terminal of the ignition coil 71 is
The other high voltage terminal of the ignition coil 71 is connected to one center electrode 6b of the ignition plug 62 of the cylinder 60b.
It is connected to the. One high-voltage terminal of the ignition coil 72 is connected to the other center electrode 6b of the ignition plug 61 of the cylinder 60a.
The other high-voltage terminal of the ignition coil 72 is connected to the other center electrode 6b of the ignition plug 62 of the cylinder 60b. One high-voltage terminal of the ignition coil 73 is connected to one center electrode 6 of the ignition plug 63 of the cylinder 60c.
b, and the other high voltage terminal of the ignition coil 73 is connected to one center electrode 6b of the ignition plug 64 of the cylinder 60d. One high-voltage terminal of the ignition coil 74 is connected to the other center electrode 6b of the ignition plug 63 of the cylinder 60c, and the other high-voltage terminal of the ignition coil 74 is connected to the other center of the ignition plug 64 of the cylinder 60d. It is connected to the electrode 6b. One high-voltage terminal of the ignition coil 75 is connected to one center electrode 6b of the ignition plug 65 of the cylinder 60e, and the other high-voltage terminal of the ignition coil 75 is connected to one center of the ignition plug 66 of the cylinder 60f. It is connected to the electrode 6b. One high-voltage terminal of the ignition coil 76 is connected to the other center electrode 6b of the ignition plug 65 of the cylinder 60e, and the other high-voltage terminal of the ignition coil 76 is connected to the other center of the ignition plug 66 of the cylinder 60f. It is connected to the electrode 6b.

FIG. 13 is a schematic diagram for explaining the connection between the ignition plug and the ignition coil when the in-cylinder fuel injection type spark ignition internal combustion engine is an inline 6 cylinder. The in-cylinder fuel injection spark ignition internal combustion engine 80 has six cylinders 80a, 80
b, 80c, 80d, 80e, and 80f, and each cylinder 80a, 80b, 80c, 80d, 80e, 80f
The mutual phase difference is 120 ° in crank angle. The ignition sequence of the in-cylinder fuel injection type spark ignition internal combustion engine 80 is as follows: cylinder 60a, cylinder 60e, cylinder 60c, cylinder 60
f, cylinder 60b, and cylinder 60d in that order.
0a, the cylinder 60c and the cylinder 60b have a phase difference of 240 ° in crank angle, and the cylinder 60e and the cylinder 6c
0f and the cylinder 60d have a phase difference of 2 in crank angle.
40 °.

Each spark plug 8 arranged in each cylinder
1, 82, 83, 84, 85, 86 have three outer electrodes (ground electrodes), not shown, and three center electrodes 6b, 6b, 6b, which are different from the spark plug 6 of the above-described embodiment. The outer electrode and the center electrode 6b forming a pair each constitute an ignition gap.

Six ignition coils 91, the same number as the number of cylinders,
Each of 92, 93, 94, 95 and 96 has three high voltage terminals. Each of the high voltage terminals of the ignition coil 91 is connected to one central electrode 6b of the ignition plug 81 of the cylinder 80a.
And one central electrode 6b of the ignition plug 82 of the cylinder 80b.
And one central electrode 6b of the ignition plug 83 of the cylinder 80c.
And connected to. Similarly to the ignition coil 91, the high voltage terminals of the ignition coil 92 are respectively connected to one central electrode 6b of the ignition plug 81 of the cylinder 80a, one central electrode 6b of the ignition plug 82 of the cylinder 80b, and ignition of the cylinder 80c. It is connected to one center electrode 6b of the plug 83. Like the ignition coil 91 and the ignition coil 92, the high voltage terminal of the ignition coil 93 is connected to the ignition plug 81 of the cylinder 80a.
And the spark plug 82 of the cylinder 80b.
And the spark plug 83 of the cylinder 80c.
Is connected to one of the center electrodes 6b.

The high voltage terminals of the ignition coil 94 are connected to one central electrode 6b of the ignition plug 84 of the cylinder 80d.
And one central electrode 6b of the ignition plug 85 of the cylinder 80e.
And one central electrode 6b of the ignition plug 86 of the cylinder 80f.
And connected to. Similarly to the ignition coil 94, the high voltage terminals of the ignition coil 95 are respectively connected to one center electrode 6b of the ignition plug 84 of the cylinder 80d, one center electrode 6b of the ignition plug 85 of the cylinder 80e, and ignition of the cylinder 80f. It is connected to one center electrode 6b of the plug 86. Like the ignition coil 94 and the ignition coil 95, the high-voltage terminal of the ignition coil 96 is connected to the ignition plug 84 of the cylinder 80d.
And the spark plug 85 of the cylinder 80e.
And the spark plug 86 of the cylinder 80f.
Is connected to one of the center electrodes 6b.

As described above, the in-cylinder fuel injection type spark ignition internal combustion engines 1, 40, 60 and 80 have a plurality of cylinders and the same number of ignition coils 31 to 32 and 51 to 5 as the number of cylinders.
4, 71 to 76, 91 to 96, and each of the ignition coils 31 to 32, 51 to 54, 71 to 76, 91 to 96
Are connected so that, among a plurality of cylinders, cylinders whose mutual phase difference is a predetermined crank angle are a set, and one ignition gap portion 6c of each of the cylinders constituting the set is simultaneously ignited. Therefore, an increase in the number of ignition coils due to a plurality of ignition gaps 6c can be suppressed, and problems such as an increase in cost, an increase in weight, and a restriction on layout of the ignition coil due to an increase in the number of ignition coils can be prevented. it can.

Further, as in the in-cylinder fuel injection type spark ignition internal combustion engines 1, 40, one ignition coil 31-32, 51
-54 are connected to each other and the ignition coil 31-32, 51-54 is connected to one ignition gap of each of the cylinders forming the set. When the cylinder 6c is connected so as to ignite at the same time, one of the cylinders forming the pair is in the exhaust-intake stroke, and a useless spark is generated in the ignition gap 6c of this cylinder. , The cylinder pressure is low, and the energy required for dielectric breakdown is low. For this reason, the energy of the ignition coils 31 to 32, 51 to 54 is injected into the ignition gap 6c of the other cylinder under the compression pressure. Energy for ignition can be reliably applied to the ignition gap 6c. Further, ignition coils 31 to 32, 51 to 54
It is possible to secure the longest charge time for the battery.

In the present embodiment, as the spray form, a spray that spreads flat in a plane including the central axis of the cylinder 8 and in a fan shape in a plane substantially perpendicular to the central axis of the cylinder 8 is exemplified. However, the spray form is not limited to this, and a swirl type or a hole type spray widely used may be used.

The shape and structure of the cavity 15 are also
The present invention is not limited to the above-described embodiment, and includes a recess having a peripheral wall surface and a bottom wall surface smoothly connected to the peripheral wall surface, and the fuel injected from the fuel injection valve toward the cavity forms an ignition plug. It may have a shape, structure, or the like in which an air-fuel mixture rising toward the air is formed.

[0049]

As described above, according to the present invention, the fuel injected from the fuel injection valve toward the cavity forms an air-fuel mixture rising toward the spark plug along the cavity. Since the ignition plug has a plurality of ignition gap portions provided at a predetermined distance so as to ignite a combustible air-fuel mixture of the air-fuel mixture rising toward the ignition plug, a plurality of ignition gaps are provided. For all of the ignition gaps, the probability that the mixture concentration around each ignition gap part simultaneously exceeds the appropriate combustible mixture concentration range is extremely small, and even if a misfire occurs in any one of the ignition gap parts, the other ignition gap The part is normally ignited, and the cylinder performs normal combustion. For this reason, the occurrence of misfire is largely suppressed. Further, if the ignition is performed at a plurality of spatially separated ignition gaps, the combustion speed in each of the ignition gaps is the same, but the combustion is accelerated in the entire cylinder. For this reason, it is possible to burn the injected fuel before it excessively diffuses to the surroundings, and it is possible to greatly suppress the occurrence of torque fluctuation. Further, fuel efficiency can be improved due to a synergistic effect of an increase in combustion efficiency and an increase in the equal capacity of the cycle. Furthermore, with a simple configuration in which the ignition plug has a plurality of ignition gap portions, the occurrence of misfire and torque fluctuation is greatly suppressed, and no significant structural change of the internal combustion engine body is involved. . As a result, an in-cylinder fuel injection type spark ignition internal combustion engine capable of obtaining stable combustion by significantly suppressing the occurrence of misfires and torque fluctuations without a significant structural change of the internal combustion engine body. Can be provided.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an in-cylinder fuel injection spark ignition internal combustion engine according to an embodiment of the present invention.

FIG. 2 is a plan view of a lower surface of a cylinder head in the in-cylinder fuel injection spark ignition internal combustion engine according to the embodiment of the present invention.

FIG. 3 is a side view of a spark plug included in the in-cylinder fuel injection spark ignition internal combustion engine according to the embodiment of the present invention.

FIG. 4 is a diagram showing the relationship between the distance between ignition gaps and the width of fuel injection timing at which stable operation is possible in the in-cylinder fuel injection type spark ignition internal combustion engine according to the embodiment of the present invention.

FIG. 5 is a diagram showing a relationship between an injection timing and a torque fluctuation value in the in-cylinder fuel injection spark ignition internal combustion engine according to the embodiment of the present invention.

FIG. 6 is a diagram showing a stable operation region in relation to an injection timing and an ignition timing in the in-cylinder fuel injection type spark ignition internal combustion engine according to the embodiment of the present invention.

FIG. 7 is a plan view of a lower surface of a cylinder bed in a modified example of the in-cylinder fuel injection type spark ignition internal combustion engine according to the embodiment of the present invention.

8A and 8B show a modified example of the in-cylinder fuel injection spark ignition internal combustion engine according to the embodiment of the present invention, wherein FIG. 8A is a plan view of a spark plug, and FIG. 8B is a side view of the spark plug.

9A and 9B show a modified example of the in-cylinder fuel injection type spark ignition internal combustion engine according to the embodiment of the present invention, wherein FIG. 9A is a plan view of an ignition plug, and FIG. 9B is a side view of the ignition plug.

FIG. 10 is a schematic diagram for explaining connection between an ignition plug and an ignition coil in the in-cylinder fuel injection type spark ignition internal combustion engine according to the embodiment of the present invention.

FIG. 11 is a schematic diagram for explaining connection between an ignition plug and an ignition coil in the in-cylinder fuel injection type spark ignition internal combustion engine according to the embodiment of the present invention.

FIG. 12 is a schematic diagram for explaining connection between an ignition plug and an ignition coil in the in-cylinder fuel injection type spark ignition internal combustion engine according to the embodiment of the present invention.

FIG. 13 is a schematic diagram for explaining connection between an ignition plug and an ignition coil in the in-cylinder fuel injection spark ignition internal combustion engine according to the embodiment of the present invention.

FIG. 14 is a diagram showing a temporal change of a mixture concentration around an ignition plug.

FIG. 15 is a diagram showing a temporal change of a mixture concentration and a flame in a cylinder.

[Explanation of symbols]

1, 40, 60, 80 ... in-cylinder fuel injection type spark ignition internal combustion engine, 6, 21 to 22, 41 to 44, 61 to 66, 81 to
86, 201: ignition plug, 6a: outer electrode, 6b: center electrode, 6c: ignition gap, 7: cylinder head,
9: cylinder block, 10: piston, 10a: top surface, 11: combustion chamber, 13, 202: fuel injection valve, 15,
203: cavity, 15a: peripheral wall surface, 15b: bottom wall surface, 31, 32, 51 to 54, 71 to 76, 91 to 96
... Ignition coils, 40a to 40d, 60a to 60f, 80
a to 80f: cylinder, M: mixture.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) H01T 13/46 H01T 13/46 (72) Inventor Hideto Inagaki 41, Nagatute-cho, Yakumichi, Nagakute-cho, Aichi-gun, Aichi Prefecture No. 1 Inside Toyota Central Research Laboratories Co., Ltd. (72) Inventor Norikatsu Ishikawa No. 41 Nagachute-cho, Aichi-gun, Aichi-gun Ochi-cho, Yokomichi Address 1 Inside Toyota Central Research Laboratories Co., Ltd. F-term (reference) 3G019 AA05 AA09 EC02 EC07 KA03 KA15 3G023 AA02 AA04 AB02 AB03 AC05 AD07 AD09 AD14 AF01 5G059 AA01 CC03 DD23 EE19

Claims (4)

[Claims] 1. A cavity comprising a recess having a peripheral wall surface and a bottom wall surface smoothly connected to the peripheral wall surface is formed on a top surface of the piston, and an ignition plug disposed above the cavity, A fuel injection valve for injecting fuel toward the cavity,
A mixture that rises toward the spark plug is formed by the fuel injected from the fuel injection valve, and the ignition plug is a combustible mixture of the mixture that rises toward the ignition plug. An in-cylinder fuel injection type spark ignition internal combustion engine having a plurality of ignition gaps provided at a predetermined distance so as to be able to ignite. 2. The in-cylinder fuel injection spark ignition internal combustion engine according to claim 1, wherein the predetermined distance is 20 mm or less. 3. The in-cylinder fuel injection type spark ignition internal combustion engine has a plurality of cylinders and the same number of ignition coils as the number of the cylinders, and each of the ignition coils is one of the plurality of cylinders. A plurality of cylinders each having a predetermined crank angle with a phase difference therebetween, and connected so as to simultaneously ignite one ignition gap of each of the cylinders forming the pair. The in-cylinder fuel injection type spark ignition internal combustion engine according to claim 1 or 2. 4. The in-cylinder fuel injection spark ignition internal combustion engine according to claim 3, wherein the predetermined crank angle is 360 °.