JP2010223189A - Ignition device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ignition device for an internal combustion engine in which the smoldering combustion of its ignition plug is reduced with regard to the ignition device of an internal combustion engine, mounted on a vehicle. <P>SOLUTION: The ignition device includes an injector 22 for ejecting fuel directly into a cylinder to generate fuel spray, and a plasma ignition plug 24 capable of ejecting plasma to a fuel spray A provided in the vicinity of the injector 22. Before the fuel spray A comes into collision with the inner wall of a combustion chamber 20, the ignition device ejects the plasma to a plasma ignition plug 24. Also, the ignition device includes a spark ignition plug 26 provided at a position distant from the injector 22 further than is the plasma ignition plug 24. Then, the ignition device allows the spark ignition plug 26 to ignite the fuel spray A. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an ignition device for an internal combustion engine mounted on a vehicle.

  Conventionally, as disclosed in Patent Document 1, for example, a direct injection spark ignition internal combustion engine in which fuel is directly injected into a combustion chamber by a fuel injection valve is known. Further, in this publication, the electrode portion of the spark ignition plug is disposed so as to be located in the fuel spray injected from the fuel injection valve or in the vicinity of the ridge line of the fuel spray, and during the fuel injection, A spray-guided combustion method that directly ignites fuel spray is disclosed. This spray-guided combustion method is a stratified combustion method in which an ideal air-fuel mixture is placed near the spark plug without causing the fuel injected from the fuel injection valve to collide with the combustion chamber wall such as a piston. Known as technology.

JP 2007-321682 A

  By the way, in the conventional internal combustion engine described above, since the electrode portion of the spark ignition plug is disposed in the fuel spray or in the vicinity of the ridgeline of the fuel spray in order to realize the spray guide type combustion, the spark ignition plug is smoldered. May occur. If the spark ignition plug smolders, there is a possibility that reliable ignition cannot be performed during stratified combustion.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide an ignition device for an internal combustion engine in which smoldering of a spark plug is reduced.

In order to achieve the above object, a first invention is an ignition device for an internal combustion engine,
A fuel injection valve that directly injects fuel into the cylinder to produce fuel spray;
A first spark plug provided in the vicinity of the fuel injection valve and capable of ejecting plasma toward the fuel spray;
First ignition means for injecting plasma to the first spark plug until the fuel spray collides with a combustion chamber wall;
A second spark plug provided at a position farther from the fuel injection valve than the first spark plug;
And a second ignition means for igniting the fuel spray on the second spark plug.

According to the first aspect of the present invention, spray guide combustion by plasma ignition can be realized by using the spark plug capable of ejecting plasma provided in the vicinity of the fuel injection valve. Since such a spark plug hardly causes smoldering, stratified combustion can be realized stably. In addition, plasma ignition can improve ignitability compared to spark ignition.
Furthermore, since the fuel spray is ignited using the two spark plugs, the high ignition energy necessary for the combustion can be shared between the first spark plug and the second spark plug. Therefore, it is possible to reduce the plasma ejection that requires a high voltage and to ensure the durability of the first spark plug. Moreover, combustion stability can be improved by performing multipoint ignition with two spark plugs.

It is a figure for demonstrating the system configuration | structure of Embodiment 1 of this invention. It is a figure for demonstrating the system configuration | structure of Embodiment 2 of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the element which is common in each figure, and the overlapping description is abbreviate | omitted.

Embodiment 1 FIG.
[System Configuration of Embodiment 1]
(overall structure)
FIG. 1 is a diagram for explaining a system configuration according to the first embodiment of the present invention. FIG. 1 shows a cross-sectional view and a plan view of the vicinity of a combustion chamber of an internal combustion engine 10 in the present embodiment. The internal combustion engine 10 shown in FIG. 1 has a plurality of cylinders (not shown). FIG. 1 shows a cross section of one of the cylinders 12. The cylinder 12 is formed in the cylinder block 14. A piston 16 is disposed in the cylinder 12 so as to be slidable with respect to the cylinder 12. A cylinder head 18 is assembled to the upper part of the cylinder block 14. A combustion chamber 20 is formed by a space surrounded by the cylinder 12, the piston 16, and the cylinder head 18 in the cylinder block 14. In the cylinder head 18, an in-cylinder injector 22 and a spark ignition plug 26 are disposed toward the combustion chamber 20. A plasma ignition plug 24 is disposed in the cylinder block 14 toward the combustion chamber 20.

  Further, the cylinder head 18 is formed with two intake ports 28 and an exhaust port 30 communicating with the combustion chamber 20. An intake valve 32 that opens and closes the intake port 28 with respect to the combustion chamber 20 is provided at the downstream end of the intake port 28. On the other hand, an exhaust valve 34 that opens and closes the exhaust port 30 with respect to the combustion chamber 20 is provided at the upstream end of the exhaust port 30.

  The system of the present embodiment includes an ECU (Electronic Control Unit) (not shown). An air flow meter, a crank angle sensor, and the like are connected to the input side of the ECU. The above-described injector 22, plasma spark plug 24, spark spark plug 26, and the like are connected to the output side of the ECU.

(Configuration of each part in the combustion chamber)
Next, the structure of each part arrange | positioned facing the combustion chamber 20 is demonstrated in detail. The injector 22 is an outer edge portion of the upper surface of the combustion chamber 20 formed in the cylinder head 18 and is disposed between the two intake valves 32. A cavity 16 a is formed on the upper surface of the piston 16. The injector 22 generates fuel spray A shown in FIG. 1 by injecting fuel (for example, gasoline is the main fuel). The injection hole of the injector 22 is set obliquely downward so that the fuel spray A collides with the cavity 16a.

  The shape of the cavity 16a is designed so that the fuel spray A colliding at a predetermined piston position is guided to the center of the upper surface of the combustion chamber 20 and a rich air-fuel mixture is collected. About the shape of the cavity 16a, since it is a well-known content, the description is abbreviate | omitted. A spark ignition plug 26 is disposed at the center of the upper surface of the combustion chamber 20. The spark ignition plug 26 is disposed at a position farther from the injector 22 than a plasma ignition plug 24 described later. The spark ignition plug 26 ignites the air-fuel mixture in the cylinder by a normal spark B.

  The plasma ignition plug 24 is disposed on the side of the cylinder block 14 and in the vicinity of the lower portion of the injector 22. The nozzle hole of the plasma spark plug 24 is set toward the fuel spray A before the collision with the cavity 16a. The plasma ignition plug 24 ignites the air-fuel mixture in the cylinder by ejecting (releasing) plasma C. While superior in directivity and ignitability, durability is inferior to spark spark plugs because high voltage is required.

(Control of ignition device)
Next, control of the ignition device in the system of the present embodiment will be described. In the system of the present embodiment, stratified combustion is performed using both the plasma ignition plug 24 and the spark ignition plug 26 in the low rotation region, and homogeneous combustion using only the spark ignition plug 26 is performed in the high rotation region. The case where stratified combustion which is the feature of this embodiment is performed will be described. When performing stratified combustion, the ECU causes the injector 22 to inject fuel during the compression stroke. The fuel spray A generated by this fuel injection is guided to the center of the upper surface of the combustion chamber 20 by the cavity 16a. That is, a rich air-fuel mixture is collected around the electrode of the spark ignition plug 26.

  The ECU causes the plasma spark plug 24 to eject the plasma C in the vicinity of the compression top dead center during fuel injection, and causes the spark spark plug 26 to spark almost simultaneously. Here, the high ignition energy required for stratified combustion of the fuel spray A is set so as to be shared by the plasma ignition plug 24 and the spark ignition plug 26.

According to the control of the ignition device described above, during stratified combustion, the plasma C having excellent directivity and ignitability can be ejected, and the fuel spray A can be directly ignited before colliding with the cavity 16a. That is, spray guide type combustion can be realized. Since the plasma ignition plug 24 provided in the vicinity of the injector 22 hardly causes smoldering, it is possible to realize reliable stratified combustion by stable ignition.
Moreover, the rich combustion gas guided to the center part of the upper surface of the combustion chamber 20 can be ignited by the spark ignition plug. Combustion stability can be improved by multipoint ignition using two spark plugs. Furthermore, by sharing the high ignition energy necessary for realizing stratified combustion between the plasma ignition plug 24 and the spark ignition plug 26, plasma injection requiring high voltage can be reduced. Durability can be improved.

In the first embodiment described above, the injector 22 is the “fuel injection valve” in the first invention, the plasma spark plug 24 is the “first spark plug” in the first invention, and the spark spark plug 26 is. Corresponds to a “second spark plug”.
Also, here, the ECU performs the spray guide type ignition using the injector 22 and the plasma spark plug 24 so that the “first ignition means” in the first invention causes the spark spark plug 26 to The “second ignition means” in the first invention is realized by igniting the air-fuel mixture in the vicinity of the top dead center.

Embodiment 2. FIG.
[System Configuration of Embodiment 2]
Next, a second embodiment of the present invention will be described with reference to FIG. The system of the present embodiment can be realized by causing the ECU to control the ignition device described in the first embodiment in the configuration shown in FIG. 2 described later. FIG. 2 is a diagram for explaining a system configuration according to the second embodiment of the present invention. The system configuration shown in FIG. 2 is the same as the system configuration of FIG. 1 described above except that the arrangement of the injector 22, the plasma spark plug 24, and the spark spark plug 26 is changed and the shape of the cavity 16a is changed. For this reason, common reference numerals are assigned to common configurations, and descriptions thereof are simplified or omitted.

(Configuration of each part in the combustion chamber)
The positions and shapes of the components arranged facing the combustion chamber 20 will be described. The injector 22 is disposed at the center of the upper surface of the combustion chamber 20 formed in the cylinder head 18. A cavity 16 a is formed on the upper surface of the piston 16. The injector 22 generates fuel spray A shown in FIG. 2 by injecting fuel. The nozzle hole of the injector 22 is set downward so that the fuel spray A collides with the cavity 16a.

  The shape of the cavity 16a is designed so that the fuel spray A colliding at a predetermined piston position is guided to the side portion on the intake side of the combustion chamber 20 to collect a rich air-fuel mixture. About the shape of the cavity 16a, since it is a well-known content, the description is abbreviate | omitted. A spark ignition plug 26 is disposed on the side surface of the cylinder block 14 located on the side of the intake side of the combustion chamber 20. The spark ignition plug 26 is disposed at a position farther from the injector 22 than a plasma ignition plug 24 described later.

  The plasma ignition plug 24 is disposed in the center of the upper surface of the combustion chamber 20 and in the vicinity of the injector 22. The nozzle hole of the plasma spark plug 24 is set toward the fuel spray A before the collision with the cavity 16a.

  In the configuration of the ignition device as described above, the same effects as those of the above-described first embodiment can be obtained by performing the control of the ignition device described in the first embodiment.

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 12 Cylinder 14 Cylinder block 16 Piston 16a Cavity 18 Cylinder head 20 Combustion chamber 22 Injector 24 Plasma ignition plug 26 Spark ignition plug 32 Intake valve 34 Exhaust valve A Fuel spray B Spark C Plasma

Claims (1)

A fuel injection valve that directly injects fuel into the cylinder to produce fuel spray;
A first spark plug provided in the vicinity of the fuel injection valve and capable of ejecting plasma toward the fuel spray;
First ignition means for injecting plasma to the first spark plug until the fuel spray collides with a combustion chamber wall;
A second spark plug provided at a position farther from the fuel injection valve than the first spark plug;
Second ignition means for igniting the fuel spray on the second spark plug;
An ignition device for an internal combustion engine, comprising:

Images